I’ve been meaning to do this for a while and finally got around to it. I’ve created a directory of the blogs I read that are authored (officially or unofficially) by Microsoft employees. It doesn’t include MVPs, partners, or other third parties, and it definitely isn’t complete.
The current iteration is missing some excellent Office-related blogs. I’ll be adding them shortly. With that caveat, who am I missing?
Ed Bott (@ wordpress.com) 
A rather dormant blog is the Windows Vista Ultimate team blog at http://windowsultimate.com/blogs/default.aspx (I know, the entire Ultimate experience appears rather dormant at the moment.)
I have the WGA blog on my watch list. http://blogs.msdn.com/wga/default.aspx
Here’s some Microsoft Office Development blogs you may be interested in. The list was compiled by Erika Ehrli. http://blogs.msdn.com/erikaehrli/archive/2007/01/24/70-office-development-bloggers-and-counting.aspx
Todd Bishop’s list at the link below, last updated 02April07, may contain some that you’ve forgotten or want to add to your list: http://blog.seattlepi.nwsource.com/microsoft/archives/109605.asp?source=rss
Regards,
Corrine