The first CTP of Visual Studio 2010 (formerly codenamed Rosario) is available for download:
http://www.microsoft.com/downloads/details.aspx?FamilyId=922B4655-93D0-4476-BDA4-94CF5F8D4814&displaylang=en

The download is 11 parts long, @ around 700MB each, and extract into a Virtual PC/Virtual Server virtual hard drive (VHD) and machine image.

I'm looking forward to getting play with this early preview release in anticipation for what I hope to be a gold release this time next year (I'm just speculating, I don't have any inside knowledge on a release date).