The future version of ASP.NET (4.0) will contain a lot of new features. Most features are already available on codeplex today (between the brackets: notice the new .NET logo revealed at the PDC as well). My personal highlights of the new coming version:

- ASP.MVC
- ASP.Dynamic Data 
- AJAX control toolkit will be included
- jQuery library will be included with intellisense support! Check jQuery today!
- Provider based caching

And for all of you tweeking the ViewState each and every day, there will be more control of the ViewState:

- Disable on page & enable on certain controls
- Disable on control, enable on children
- GridView / ListView work better without Viewstate

For all the details watch the Scott Hunter talk about ASP.NET 4.0 at channel 9: http://channel9.msdn.com/pdc2008/PC20/ and download the session slides.