I've upgraded MS Exchange 2003 to SP2 and installed a dozen critical security updates, a firmware update to the PERC/3 RAID array controller. Wicked fun! (That means I mostly sat around while little blue bars crawled across the screen, over and over).
I did get to run the ExBPA tool, and I found 4 critical problems. One is expected - we're apparently purposely blocking the SMTP port with our antivirus/firewall solution. One was a simple registry fix to prevent possible memory corruption. The other two errors related to deleted folders which had not been correctly cleared from the folder store object.
This is an amazing little tool and I hope MS releases more of these. This, the security baseline tool, the disaster recovery tool etc. Anything that can make my job easier is a GOOD THING.