I'll be updating the SQL dev center this week to get all of the new content into the appropriate places in the information architecture there, but in the meantime, here's a quick rundown of the content that's gone up in the last week or so:
and the not-Analysis Services-but-still-BI-related:
Lots of good information straight from the product team for those of you thinking about creating or updating a data warehouse on 2005.
Addendum: Per Mosha's comment, here's an additional TechNet AS 2005 whitepaper. This one'll be a little more DBA focused than the MSDN pieces above: