I'm getting ready to dig into SQL Server 2008 a bit over the next few months.  While I was surfing around looking for what's available, I came across some recorded on demand webcasts at https://connect.microsoft.com/SQLServer/content/content.aspx?ContentID=5553.  The page says there are more webcasts to come.  Here's what's up there now:

Analysis Services - Dimension Design
Change Data Capture
Star Join Query Optimizations
Table Valued Parameters
Declarative Management Framework
MERGE SQL Statement

-Marc