In v2, the caching engine for ASP.NET will get improved to include some of the most frequently requested features for 1.x. Namely, support for database cache invalidation and custom cache dependencies will be added, allowing for much more powerful and intelligent caching scenarios to be set up.
For more information on caching in 1.x:
MSDN: Creating a Cache Configuration Object in ASP.NET
Discuss Caching in Whidbey