SQL Server 2008(formerly codename "Katmai") Public CTP now available

You can get the CTP here and Dave Campbell did/is doing a web cast here.

Enjoy, however remember one of the changes in the SQL Server Team's process is that features will not appear in a build until they are "complete" so there are not heaps and heaps of features but the ones that are there should be complete, and the base level of performance/stability should not be far off SQL 2005 RTM.

Update, here is the link to Dave's session, it was recorded