A must read blog?
Steven Sinofsky and Jon DeVaan - the 2 guys who manage the Windows dev team have started blogging at http://blogs.msdn.com/e7/
At first glance, this blog looks mainly interesting if you are keen on Windows 7- but if you check out one of their first entries, you will quickly see that this is useful for anyone trying to understand the complexities of building large software. I read the Windows 7 Team post last night and it is truly fascinating. I find the comments just as useful.
BTW Steven blogs internally at Microsoft and his blog entries are LONG!.