In all of the hectic activity of the last couple of months I missed a couple of important partner announcements.  Two (at least, I may find more I've missed yet) partners have released support for Team System in the past couple of months.

VersionOne - VersionOne is one of the leading Agile project management tools in the market.  In early August they released support for TFS integration.  You can find details in the press release here: http://www.reuters.com/article/pressRelease/idUS143424+05-Aug-2008+PRN20080805

TX Chrono - TX Chrono, by TeamExpand, is a time tracking add-on to Team System that allows users to easily track how they are spending their time and store that information in TFS and make it available for reporting in the warehouse.  You can learn more about TX Chrono here: http://teamexpand.com/product/tx-chrono

Brian