diff --git a/doc/play/playground.js b/doc/play/playground.js
index ce9aa27b49f..6f1a5c7a2ee 100644
--- a/doc/play/playground.js
+++ b/doc/play/playground.js
@@ -1,6 +1,197 @@
-// Copyright 2011 The Go Authors. All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// A dummy playground.js file to silence godoc errors
-// when accessing doc/root.html.
+// opts is an object with these keys
+// 	codeEl - code editor element 
+// 	outputEl - program output element
+// 	runEl - run button element
+// 	shareEl - share button element (optional)
+// 	shareURLEl - share URL text input element (optional)
+// 	preCompile - callback to mutate request data before compiling
+// 	postCompile - callback to read response data after compiling
+//      simple - use plain textarea instead of CodeMirror.
+function playground(opts) {
+	var simple = opts['simple'];
+	var code = $(opts['codeEl']);
+	var editor;
+
+	// autoindent helpers for simple mode.
+	function insertTabs(n) {
+		// find the selection start and end
+		var start = code[0].selectionStart;
+		var end   = code[0].selectionEnd;
+		// split the textarea content into two, and insert n tabs
+		var v = code[0].value;
+		var u = v.substr(0, start);
+		for (var i=0; i<n; i++) {
+			u += "\t";
+		}
+		u += v.substr(end);
+		// set revised content
+		code[0].value = u;
+		// reset caret position after inserted tabs
+		code[0].selectionStart = start+n;
+		code[0].selectionEnd = start+n;
+	}
+	function autoindent(el) {
+		var curpos = el.selectionStart;
+		var tabs = 0;
+		while (curpos > 0) {
+			curpos--;
+			if (el.value[curpos] == "\t") {
+				tabs++;
+			} else if (tabs > 0 || el.value[curpos] == "\n") {
+				break;
+			}
+		}
+		setTimeout(function() {
+			insertTabs(tabs, 1);
+		}, 1);
+	}
+
+	function keyHandler(e) {
+		if (simple && e.keyCode == 9) { // tab
+			insertTabs(1);
+			e.preventDefault();
+			return false;
+		}
+		if (e.keyCode == 13) { // enter
+			if (e.shiftKey) { // +shift
+				run();
+				e.preventDefault();
+				return false;
+			} else if (simple) {
+				autoindent(e.target);
+			}
+		}
+		return true;
+	}
+	if (simple) {
+		code.unbind('keydown').bind('keydown', keyHandler);
+	} else {
+		editor = CodeMirror.fromTextArea(
+			code[0],
+			{
+				lineNumbers: true,
+				indentUnit: 8,
+				indentWithTabs: true,
+				onKeyEvent: function(editor, e) { keyHandler(e); }
+			}
+		);
+	}
+	var output = $(opts['outputEl']);
+
+	function clearErrors() {
+		if (!editor) {
+			return;
+		}
+		var lines = editor.lineCount();
+		for (var i = 0; i < lines; i++) {
+			editor.setLineClass(i, null);
+		}
+	}
+	function highlightErrors(text) {
+		if (!editor) {
+			return;
+		}
+		var errorRe = /[a-z]+\.go:([0-9]+): /g;
+		var result;
+		while ((result = errorRe.exec(text)) != null) {
+			var line = result[1]*1-1;
+			editor.setLineClass(line, "errLine")
+		}
+	}
+	function body() {
+		if (editor) {
+			return editor.getValue();
+		}
+		return $(opts['codeEl']).val();
+	}
+
+	var seq = 0;
+	function run() {
+		clearErrors();
+		output.removeClass("error").html(
+			'<div class="loading">Waiting for remote server...</div>'
+		);
+		seq++;
+		var cur = seq;
+		var data = {"body": body()};
+		if (opts['preCompile']) {
+			opts['preCompile'](data);
+		}
+		$.ajax("/compile", {
+			data: data,
+			type: "POST",
+			dataType: "json",
+			success: function(data) {
+				if (seq != cur) {
+					return;
+				}
+				pre = $("<pre/>");
+				output.empty().append(pre);
+				if (opts['postCompile']) {
+					opts['postCompile'](data);
+				}
+				if (!data) {
+					return;
+				}
+				if (data.compile_errors != "") {
+					pre.text(data.compile_errors);
+					output.addClass("error");
+					highlightErrors(data.compile_errors);
+					return;
+				}
+				var out = ""+data.output;
+				if (out.indexOf("IMAGE:") == 0) {
+					var img = $("<img/>");
+					var url = "data:image/png;base64,";
+					url += out.substr(6)
+					img.attr("src", url);
+					output.empty().append(img);
+					return;
+				}
+				pre.text(out);
+			},
+			error: function() {
+				output.addClass("error").text(
+					"Error communicating with remote server."
+				);
+			}
+		});
+	}
+	$(opts['runEl']).click(run);
+
+	if (opts['shareEl'] == null || opts['shareURLEl'] == null) {
+		return editor;
+	}
+
+	function origin(href) {
+		return (""+href).split("/").slice(0, 3).join("/");
+	}
+
+	var shareURL = $(opts['shareURLEl']).hide();
+	var sharing = false;
+	$(opts['shareEl']).click(function() {
+		if (sharing) return;
+		sharing = true;
+		$.ajax("/share", {
+			processData: false,
+			data: body(),
+			type: "POST",
+			complete: function(xhr) {
+				sharing = false;
+				if (xhr.status != 200) {
+					alert("Server error; try again.");
+					return
+				}
+				var url = origin(window.location) + "/p/" +
+					xhr.responseText;
+				shareURL.show().val(url).focus().select();
+			}
+		});
+	});
+
+	return editor;
+}
diff --git a/doc/root.html b/doc/root.html
index 7007dceb4be..20bd62b2741 100644
--- a/doc/root.html
+++ b/doc/root.html
@@ -26,7 +26,7 @@ Linux, Mac OS X, Windows, and more.
 <div id="learn">
 <div class="rootHeading">Try Go</div>
 <div class="input">
-<textarea spellcheck="false">// You can edit this code!
+<textarea spellcheck="false" id="code">// You can edit this code!
 // Click here and start typing.
 package main
 
@@ -36,14 +36,14 @@ func main() {
 	fmt.Println("Hello, 世界")
 }</textarea>
 </div>
-<div class="output">
+<div class="output" id="output">
 <pre>
 Hello, 世界
 </pre>
 </div>
 <div class="buttons">
-<a href="#">Run</a>
-<a href="#">Share</a>
+<a id="run" href="#">Run</a>
+<a id="share" href="#">Share</a>
 </div>
 </div>
 
@@ -75,39 +75,52 @@ Hello, 世界
 <div id="plusoneRoot"><g:plusone annotation="none"></g:plusone></div>
 
 <script type="text/javascript" src="https://www.google.com/jsapi"></script>
-<script>
+<script type="text/javascript" src="/doc/play/playground.js"></script>
+<script type="text/javascript">
 google.load("feeds", "1");
+google.load("jquery", "1.7.1");
 
 function feedLoaded(result) {
-  if (result.error) {
-    console.log(result.error);
-    return;
-  }
-  var blog = document.getElementById("blog");
-  var read = blog.getElementsByClassName("read")[0];
-  for (var i = 0; i < result.feed.entries.length && i < 2; i++) {
-    var entry = result.feed.entries[i];
-    var title = document.createElement("a");
-    title.className = "title";
-    title.href = entry.link;
-    title.innerHTML = entry.title;
-    blog.insertBefore(title, read);
-    var extract = document.createElement("div");
-    extract.className = "extract";
-    extract.innerHTML = entry.contentSnippet;
-    blog.insertBefore(extract, read);
-    var when = document.createElement("div");
-    when.className = "when";
-    var pub = entry.publishedDate.split(" ").slice(1,3).join(" ");
-    when.innerHTML = "Published " + pub
-    blog.insertBefore(when, read);
-  }
+	if (result.error) {
+		console.log(result.error);
+		return;
+	}
+	var blog = document.getElementById("blog");
+	var read = blog.getElementsByClassName("read")[0];
+	for (var i = 0; i < result.feed.entries.length && i < 2; i++) {
+		var entry = result.feed.entries[i];
+		var title = document.createElement("a");
+		title.className = "title";
+		title.href = entry.link;
+		title.innerHTML = entry.title;
+		blog.insertBefore(title, read);
+		var extract = document.createElement("div");
+		extract.className = "extract";
+		extract.innerHTML = entry.contentSnippet;
+		blog.insertBefore(extract, read);
+		var when = document.createElement("div");
+		when.className = "when";
+		var pub = entry.publishedDate.split(" ").slice(1,3).join(" ");
+		when.innerHTML = "Published " + pub
+		blog.insertBefore(when, read);
+	}
 }
 
-function fetchFeeds() {
-  var feed = new google.feeds.Feed("http://blog.golang.org/feeds/posts/default");
-  feed.load(feedLoaded);
+function init() {
+	// Load blog feed.
+	var feed = new google.feeds.Feed("http://blog.golang.org/feeds/posts/default");
+	feed.load(feedLoaded);
+
+	// Set up playground.
+	playground({
+		"simple":     true,
+		"codeEl":     "#code",
+		"outputEl":   "#output",
+		"runEl":      "#run",
+		"shareEl":    "#share",
+		"shareURLEl": "#shareURL"
+	});
 }
 
-google.setOnLoadCallback(fetchFeeds);
+google.setOnLoadCallback(init);
 </script>
diff --git a/doc/style.css b/doc/style.css
index 68a43f9b21b..13a0e04ee4d 100644
--- a/doc/style.css
+++ b/doc/style.css
@@ -227,6 +227,7 @@ body {
 }
 
 #learn pre, #learn textarea {
+	padding: 0;
 	margin: 0;
 	font-family: Menlo, monospace;
 	font-size: 14px;