In addition to shipping VS 2008 and .NET 3.5 Beta 2 last week, my team also shipped the first release candidate of Silverlight 1.0 (it was a busy week at the office!). You can download the Silverlight 1.0 RC here.
You can learn all about Justin's library via his excellent tutorial post here. You can then download and participate in the codeplex project here.
Hope this helps,
P.S. All of the intellisense features above work in both VS 2008 as well as the free Visual Web Developer 2008 Express Edition.