I came across two very interesting web sites lately, both of which are a great source for good webcasts. The first site is Learn Microsoft BI which has all sorts of video on BI projects and how to develop them using SSAS. There has actually just been a first video on PerformancePoint Server as well. The site requires registration, but is well worth it.
The other site is SQL Server Videos which targets more DBAs and developers.
Having done just a few webcasts and knowing how much work goes into it, I am in complete awe of what’s given in both sites. I strongly recommend you check both of them out.
Update 28/10/08: Microsoft has added videos to its MSDN catalog of Books Online for SQL Server 2008.