Unfortunately Jim Allchin did stick to his plans and left Microsoft after Windows Vista was RTMed.
I highly respect what he has accomblished in the last 17 years and hope that he's coming back to the blog-o-sphere more personally.
Read his last post while being in the job - it's hollarious!
http://windowsvistablog.com/blogs/windowsvista/arc...
I'm sad he left, but wish him all the best for the future!