I was at Microsoft campus today and I had a chance to catch up with Michal Gideoni to discuss SharePoint field readiness.  We chatted about certification exams, SharePoint documentation, whitepapers and instructional videos.  We also discussed the latest post she wrote for the SharePoint Team blog (http://blogs.msdn.com/sharepoint/archive/2008/02/18/advanced-sharepoint-videos-and-whitepapers.aspx).  This post provides a good list of whitepapers and videos relating to several advanced topics.  It is well worth a bookmark.