There are a number of the “Exchange Insider” articles starting to trickle out onto the TechCenter site at: http://www.microsoft.com/technet/prodtechnol/exchange/2003/insider/default.mspx
In case you’re not familiar with these articles, they come from a weekly “tech bulletin” started a few years ago by one of the tech support leads in the Texas site. Over the years these weekly emails have hosted various guest writers on many interesting Exchange (and Exchange-related) topics. I’ve even been known to write a bulletin every now and then. 
Hopefully you’ll find them as useful as we do internally!