Well it seems the folks in Redmond are at it again -- specifically the Microsoft Learning team. What's going on, you say? They are listening and ch-ch-ch-ch-changing (David Bowie homage). Here, let me explain:
By passing the 70-620 exam, you earn the MCTS: Vista Configuration certification. Nothing new there. However when you pass the 70-621 MCDST upgrade to MCITP: Enterprise, you earn both your MCITP: Enterprise AND MCTS: Vista Configuration! Wait... Nothing new there either. So what has changed? Well listen up...
For those certification that required you take and pass the 70-620 as a client requirement, you can now use the 70-621 in place of this. Before this announcement, you had to take the 70-620 even though you already received the credit and certification transitively by passing the 70-621. Not anymore. The good folks at MSL looked at the math again and determined that the original math did not make sense -- I would imagine that the hundreds of emails and complaints concerning this issue also had something to do with this change. Regardless, props to the MSL team for realizing this did not make sense and changing it.
p.s. I have been known to make stuff up, so if you really want straight from the horse's mouth visit Trika's blog at http://blogs.msdn.com/trika/archive/2007/09/19/get-rich-quick-scheme-for-mcdsts.aspx
p.s.s. Trika, that is not to say you are a horse. You know I love ya!
p.s.s.s The flowers are on their way. Building 18 right?