"Gwt Query is a jQuery-like API written in GWT, which allows GWT to be used in progressive enhancement scenarios where perhaps GWT widgets are too heavyweight. Currently, about 98% of the jQuery API is written. Most CSS3 selectors are supported. People feel free to contribute patches to bring the API more in line with jQuery."

Project Home:

http://code.google.com/p/gwtquery/

Quickstart guide:

http://code.google.com/p/gwtquery/wiki/GettingStarted

Google I/O Presentation:

http://code.google.com/events/io/2009/sessions/ProgressivelyEnhanceAjaxA...

Microsoft AJAX CDN is a free service that allows our web apps get served with JQuery, MS Ajax, and images, from MS servers near the requesting browser.

Here is a nice "how to" article that describes how to use a star rating  JQuery addon together with ASP.NET MVC.

Visual Studio 2008 support Java Script IntelliSense. It does so by using a "-vsdoc.js" file, which is saved together with the "original" ".js" file. For example, if you're using JQuery, and use jquery-1.3.2.min.js file, you can put a jquery-1.3.2.min-vsdoc.js file just next to it (available from JQuery download page), and that's it.

Unfortunately, this may not work, and all you get is: "Error updating JScript IntelliSense: Object doesn't support this property or method".

One of the things may cause this issue is a bug in Visual Studio. If you're using Visual Studio 2008 SP1 (like I do), there's a patch you can install that adds JScript Editor support for “-vsdoc.js” IntelliSense documentation files.