Anyhow, things have changed quite a bit since then and I immediately knew it would be great to have Intelisense working for jQuery! There are several steps involved though but through much trial & error I've finally got it working properly. Hopefully others will benefit from my efforts.
How Do You Know if jQuery Intellisense is Working?
Simply go to a location where you'd normally enter Javascript code and type a dollar sign ("$"). A pop-up menu will appear. What it displays gives you an immediate indication of whether jQuery Intellisense is functioning. Here's a development environment where it's not working:


Something akin to the following should then appear in the pop-up menu:

Getting jQuery Intellisense Up & Running
- Ensure that VS2008 SP1 is installed. (Further info)
- Ensure that Hotfix KB958502 is installed. (Further info)
- Install the jQuery library into your project. It'll have a filename like "jquery-1.3.2.js".
- Install the jQuery Intellisense file into your project. It may very well have a filename like "jquery-1.3.2-vsdoc2.js" but must be renamed to be identical to the jQuery library name, plus "-vsdoc". Thus in this example, it must be renamed to "jquery-1.3.2-vsdoc.js".
- Provide a reference to the jQuery library. There are generally two ways to do this, both of which are described below.
- In external Javascript files a direct reference to the jQuery Intellisense file must be made. More details are provided below.
Referencing the jQuery Library and the jQuery Intellisense File
I'm a big believer in:
- Organizing a project's files into as many sub-folders as makes sense.
- Separating programming code from markup code as much as possible.


Accessing jQuery Intellisense in an External Javascript File
As mentioned previously, I like to place as much Javascript (and jQuery) code into external Javascript files (those ending in ".js") as is practical. If you use the same approach then you will face a disappointment if you're expecting Intellisense to work properly in such a file:

The solution is very simple though. Just add a reference like this to the top of the file:
/// <reference path="jquery-1.3.2-vsdoc.js" />
Then the Intellisense you enjoy in ASPX files will also work in external Javascript files too! Here's an example:

Final Caveat
A little while ago I presented a way to programatically load jQuery entirely from server-side code. It does work and is powerful because a common server-side method could be built and then used in all of your projects. But jQuery Intellisense will not work using that approach; at least not with VS2008. Perhaps that will change in VS2010!