Just wanted to point to David Weiss's outstanding blog; David works on Mac apps at Microsoft, and posts about fascinating (uh, to me at least) behind-the-scenes stuff:

• A Tour of Microsoft's Mac Lab (where they do automated QA testing)
• Mac Lab Questions and Answers (from commenters on the above post)
• Questions about UI Design (regarding Office for Mac)
• Glossy MacBook (on the just-announced MacBook)