The strongly typed nature of TypeScript offers the potential for amazing IntelliSense!
Open Source TypeScript Definitions
TypeScript Definitions on NuGet
The best thing about the open source community: whenever someone has a great idea, other people gladly line up to help improve it. To that end people have forked Boris's DefinitelyTyped, created NuGet packages, and automated their deployment!
If you want to use jQuery, just install the jquery.TypeScript.DefinitelyTyped NuGet package...
...add a reference tag to your file, and start enjoying full jQuery IntelliSense!