You can learn more about this new dynamic data preview and
download and run it locally here.
You can watch David Ebbo's dynamic
data presentation at MIX 08 to learn more about how it works. Also
check out Scott Hunter's screen-cast here, and Brad Millington's screen cast here. David also has a post here that talks about the changes made between the December
preview and today's preview release.
You can ask questions and submit feedback via the www.asp.net forums here.
Hope this helps,