diff --git a/Gruntfile.js b/Gruntfile.js
index 5edad075..bd21d089 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -7,6 +7,7 @@ module.exports = function(grunt) {
     grunt.loadNpmTasks("grunt-contrib-qunit");
     grunt.loadNpmTasks("grunt-contrib-connect");
     grunt.loadNpmTasks("grunt-contrib-watch");
+    grunt.loadNpmTasks("grunt-contrib-clean");
 
     var distribution = "build/openseadragon/openseadragon.js",
         minified = "build/openseadragon/openseadragon.min.js",
@@ -43,6 +44,19 @@ module.exports = function(grunt) {
     // Project configuration.
     grunt.initConfig({
         pkg: grunt.file.readJSON("package.json"),
+        clean: {
+            build: ["build"],
+            release: {
+                src: [
+                    "../site-build/openseadragon",
+                    "../site-build/openseadragon.zip",
+                    "../site-build/openseadragon.tar"
+                ],
+                options: {
+                    force: true
+                }
+            }
+        },
         concat: {
             options: {
                 banner: "/**\n * @version  <%= pkg.name %> <%= pkg.version %>\n */\n\n"
@@ -93,7 +107,7 @@ module.exports = function(grunt) {
         },
         watch: {
             files: [ "grunt.js", "src/*.js" ],
-            tasks: "default"
+            tasks: "build"
         },
         jshint: {
             options: {
@@ -109,20 +123,45 @@ module.exports = function(grunt) {
         }
     });
 
-    // Copy task.
-    grunt.registerTask("copy", function() {
+    // Copy:build task.
+    // Copies the image files into the appropriate location in the build folder.
+    grunt.registerTask("copy:build", function() {
         grunt.file.recurse("images", function(abspath, rootdir, subdir, filename) {
             grunt.file.copy(abspath, "build/openseadragon/images/" + (subdir || "") + filename);            
         });
     });
 
-    // Default task.
-    grunt.registerTask("default", ["jshint:beforeconcat", "concat", "jshint:afterconcat", "uglify", "copy"]);
+    // Copy:release task.
+    // Copies the contents of the build folder into ../site-build.
+    grunt.registerTask("copy:release", function() {
+        grunt.file.recurse("build", function(abspath, rootdir, subdir, filename) {
+            var dest = "../site-build/"
+                + (subdir ? subdir + "/" : "")
+                + filename;
+
+            grunt.file.copy(abspath, dest);
+        });
+    });
+
+    // Build task.
+    // Cleans out the build folder and builds the code and images into it, checking lint.
+    grunt.registerTask("build", [
+        "clean:build", "jshint:beforeconcat", "concat", "jshint:afterconcat", "uglify", "copy:build"
+    ]);
 
     // Test task.
-    grunt.registerTask("test", ["default", "connect", "qunit"]);
+    // Builds and runs unit tests.
+    grunt.registerTask("test", ["build", "connect", "qunit"]);
 
     // Package task.
-    grunt.registerTask("package", ["default", "compress"]);
+    // Builds and creates the .zip and .tar files.
+    grunt.registerTask("package", ["build", "compress"]);
 
+    // Publish task.
+    // Cleans the built files out of ../site-build and copies newly built ones over.
+    grunt.registerTask("publish", ["package", "clean:release", "copy:release"]);
+
+    // Default task.
+    // Does a normal build.
+    grunt.registerTask("default", ["build"]);
 };
diff --git a/README.md b/README.md
index e84f2fc9..d37c0cb1 100644
--- a/README.md
+++ b/README.md
@@ -46,6 +46,14 @@ If you want to build tar and zip files for distribution (they will also appear i
 
     grunt package
 
+Note that the `build` folder is masked with .gitignore; it's just for your local use, and won't be checked in to the repository.
+
+You can also publish the built version to the site-build repository. This assumes you have cloned it next to this repository. The command is:
+
+    grunt publish
+
+... which will delete the existing openseadragon folder, along with the .zip and .tar files, out of the site-build folder and replace them with newly built ones from the source in this repository; you'll then need to commit the changes to site-build.
+
 ## Testing
 
 Our tests are based on [QUnit](http://qunitjs.com/) and [PhantomJS](http://phantomjs.org/); they're both installed when you run `npm install`. At the moment we don't have much in the way of tests, but we're working to fix that. To run on the command line:
diff --git a/package.json b/package.json
index 2daf64b9..b0daa42d 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "OpenSeadragon",
-  "version": "0.9.120",
+  "version": "0.9.121",
   "description": "Provides a smooth, zoomable user interface for HTML/Javascript.",
   "dependencies": {
     "grunt": "~0.4.0",
@@ -10,7 +10,8 @@
     "grunt-contrib-uglify": "~0.1.1",
     "grunt-contrib-qunit": "~0.1.1",
     "grunt-contrib-connect": "~0.1.2",
-    "grunt-contrib-watch": "~0.2.0"
+    "grunt-contrib-watch": "~0.2.0",
+    "grunt-contrib-clean": "~0.4.0"
   },
   "scripts": {
     "test": "grunt test"
diff --git a/src/mousetracker.js b/src/mousetracker.js
index 9fd9ffbe..397fd19f 100644
--- a/src/mousetracker.js
+++ b/src/mousetracker.js
@@ -695,6 +695,10 @@
             THIS[ tracker.hash ].lastPinchDelta = 
                 Math.abs( touchA.x - touchB.x ) +
                 Math.abs( touchA.y - touchB.y );
+            THIS[ tracker.hash ].pinchMidpoint = new $.Point(
+                ( touchA.x + touchB.x ) / 2 ,
+                ( touchA.y + touchB.y ) / 2
+            );
             //$.console.debug("pinch start : "+THIS[ tracker.hash ].lastPinchDelta);
         }
 
@@ -756,6 +760,7 @@
         }
         if( event.touches.length + event.changedTouches.length == 2 ){
             THIS[ tracker.hash ].lastPinchDelta = null;
+            THIS[ tracker.hash ].pinchMidpoint  = null;
             //$.console.debug("pinch end");
         }
         event.preventDefault();
@@ -961,8 +966,8 @@
 
                 onMouseWheelSpin( tracker, {
                     shift: false,
-                    pageX: ( event.touches[ 0 ].pageX + event.touches[ 1 ].pageX ) / 2,
-                    pageY: ( event.touches[ 0 ].pageY + event.touches[ 1 ].pageY ) / 2,
+                    pageX: THIS[ tracker.hash ].pinchMidpoint.x,
+                    pageY: THIS[ tracker.hash ].pinchMidpoint.y,
                     detail:( 
                         THIS[ tracker.hash ].lastPinchDelta > pinchDelta 
                     ) ? 1 : -1