diff --git a/core/src/main/java/hudson/Functions.java b/core/src/main/java/hudson/Functions.java
index 148dfd64e9..12a53246c1 100644
--- a/core/src/main/java/hudson/Functions.java
+++ b/core/src/main/java/hudson/Functions.java
@@ -21,9 +21,23 @@ import java.io.File;
 import javax.servlet.http.HttpServletResponse;
 
 /**
+ * Utility functions used in views.
+ *
+ * <p>
+ * An instance of this class is created for each request.
+ *
  * @author Kohsuke Kawaguchi
  */
 public class Functions {
+    private int iota=0;
+
+    /**
+     * Generates an unique ID.
+     */
+    public String generateId() {
+        return "id"+iota++;
+    }
+
     public static boolean isModel(Object o) {
         return o instanceof ModelObject;
     }
diff --git a/core/src/main/java/hudson/model/Executor.java b/core/src/main/java/hudson/model/Executor.java
index 4ed48d08c8..8af955004a 100644
--- a/core/src/main/java/hudson/model/Executor.java
+++ b/core/src/main/java/hudson/model/Executor.java
@@ -6,6 +6,9 @@ import org.kohsuke.stapler.StaplerResponse;
 import javax.servlet.ServletException;
 import java.io.IOException;
 
+import hudson.Functions;
+import hudson.Util;
+
 
 /**
  * Thread that executes builds.
@@ -114,6 +117,23 @@ public class Executor extends Thread {
         return num;
     }
 
+    /**
+     * Computes a human-readable text that shows the expected remaining time
+     * until the build completes.
+     */
+    public String getEstimatedRemainingTime() {
+        Build b = build.getProject().getLastSuccessfulBuild();
+        if(b==null)     return "N/A";
+
+        long duration = b.getDuration();
+        if(duration==0) return "N/A";
+
+        long eta = duration-(System.currentTimeMillis()-startTime);
+        if(eta<=0)      return "N/A";
+
+        return Util.getTimeSpanString(eta);
+    }
+
     /**
      * Stops the current build.
      */
diff --git a/core/src/main/resources/hudson/model/Job/buildHistory.jelly b/core/src/main/resources/hudson/model/Job/buildHistory.jelly
index 340d671873..98f6bc6815 100644
--- a/core/src/main/resources/hudson/model/Job/buildHistory.jelly
+++ b/core/src/main/resources/hudson/model/Job/buildHistory.jelly
@@ -53,7 +53,7 @@
         <tr><td></td><td style="padding:0">
           <table class="middle-align">
             <tr><td>
-              <t:progressBar pos="${build.executor.progress}" href="${link}console"/>
+              <t:buildProgressBar build="${build}"/>
             </td><td style="padding:0">
               <a href="${link}stop"><img src="${rootURL}/images/16x16/stop.gif" alt="[cancel]"/></a>
             </td></tr>
diff --git a/core/src/main/resources/lib/hudson/buildCaption.jelly b/core/src/main/resources/lib/hudson/buildCaption.jelly
index 17e5c16a40..a6f45cb8ca 100644
--- a/core/src/main/resources/lib/hudson/buildCaption.jelly
+++ b/core/src/main/resources/lib/hudson/buildCaption.jelly
@@ -9,7 +9,7 @@
 	        <td>
 	          Progress:
 	        </td><td>
-	          <t:progressBar pos="${it.executor.progress}"/>
+	          <t:buildProgressBar build="${it}"/>
 	        </td><td>
 	          <a href="stop"><img src="${rootURL}/images/16x16/stop.gif" alt="[cancel]" /></a>
 	        </td>
diff --git a/core/src/main/resources/lib/hudson/buildProgressBar.jelly b/core/src/main/resources/lib/hudson/buildProgressBar.jelly
new file mode 100644
index 0000000000..4bcc41ce04
--- /dev/null
+++ b/core/src/main/resources/lib/hudson/buildProgressBar.jelly
@@ -0,0 +1,16 @@
+<!--
+  Progress bar for a build in progress.
+
+  Attributes:
+    @build: build in progress
+-->
+<j:jelly xmlns:j="jelly:core" xmlns:x="jelly:xml" xmlns:st="jelly:stapler" xmlns:d="jelly:define" xmlns:l="/lib/layout" xmlns:t="/lib/hudson" xmlns:f="/lib/form">
+  <j:set var="id" value="${h.generateId()}"/>
+  <t:progressBar id="${id}" pos="${build.executor.progress}" href="${rootURL}/${build.url}console"/>
+  <script>
+    new YAHOO.widget.Tooltip("tooltip-${id}", {
+	    context:"${id}",
+      text:"Started ${build.timestampString} ago&lt;br> Estimated remaining time: ${build.executor.estimatedRemainingTime}",
+	    showDelay:500 } );
+  </script>
+</j:jelly>
diff --git a/core/src/main/resources/lib/hudson/executors.jelly b/core/src/main/resources/lib/hudson/executors.jelly
index de59a63700..62f42b046f 100644
--- a/core/src/main/resources/lib/hudson/executors.jelly
+++ b/core/src/main/resources/lib/hudson/executors.jelly
@@ -43,7 +43,7 @@
 	          <j:otherwise>
 	            <td class="pane" width="70%">
 	              <div nowrap="true">Building <a href="${rootURL}/${e.currentBuild.url}">${e.currentBuild}</a></div>
-	              <t:progressBar pos="${e.progress}" href="${rootURL}/${e.currentBuild.url}console"/>
+                <t:buildProgressBar build="${e.currentBuild}"/>
 	            </td>
 	            <td class="pane" width="16" align="center" valign="middle">
 	              <a href="${rootURL}/computers/${cloop.index}/executors/${eloop.index}/stop"><img src="${rootURL}/images/16x16/stop.gif" alt="terminate this build" /></a>
diff --git a/core/src/main/resources/lib/hudson/progressBar.jelly b/core/src/main/resources/lib/hudson/progressBar.jelly
index ba95b51df3..9d7b710c3f 100644
--- a/core/src/main/resources/lib/hudson/progressBar.jelly
+++ b/core/src/main/resources/lib/hudson/progressBar.jelly
@@ -7,7 +7,10 @@
 <j:jelly xmlns:j="jelly:core" xmlns:x="jelly:xml" xmlns:st="jelly:stapler" xmlns:d="jelly:define" xmlns:l="/lib/layout" xmlns:t="/lib/hudson" xmlns:f="/lib/form">
 	<x:element name="table">
 		<x:attribute name="class">progress-bar</x:attribute>
-	  <j:if test="${href!=null}">
+    <j:if test="${attrs.id!=null}">
+      <x:attribute name="id">${id}</x:attribute>
+    </j:if>
+    <j:if test="${href!=null}">
 	  	<x:attribute name="style">cursor:pointer</x:attribute>
 	    <x:attribute name="onclick">window.location='${href}'</x:attribute>
       <!-- note that this won't take effect in browsers that don't let JavaScript change status bar, like Firefox. -->
diff --git a/core/src/main/resources/lib/layout/layout.jelly b/core/src/main/resources/lib/layout/layout.jelly
index 77eced6a61..39e2d70ca9 100644
--- a/core/src/main/resources/lib/layout/layout.jelly
+++ b/core/src/main/resources/lib/layout/layout.jelly
@@ -22,14 +22,12 @@
     <script src="${rootURL}/scripts/sortable.js" type="text/javascript"></script>
     <script src="${rootURL}/scripts/hudson-behavior.js" type="text/javascript"></script>
 
-    <!-- include YUI scripts
     <j:set var="yuiSuffix" value="${h.yuiSuffix}" />
     <script src="${rootURL}/scripts/yui/yahoo-${yuiSuffix}.js"></script>
     <script src="${rootURL}/scripts/yui/dom-${yuiSuffix}.js"></script>
     <script src="${rootURL}/scripts/yui/event-${yuiSuffix}.js"></script>
     <script src="${rootURL}/scripts/yui/container-${yuiSuffix}.js"></script>
     <link rel="stylesheet" href="${rootURL}/scripts/yui/container.css" type="text/css"/>
-    -->
     
     <meta name="ROBOTS" content="INDEX,NOFOLLOW" />
     <j:set var="mode" value="header" />