Well... just took Exchange 2010 (70-662) today and passed. Overall not a hard test. I may have over prepared for the test a bit. But nothing is wrong with learning more than needed. Note: I am an Exchange administrators and MCITP on Exchange 2007 so this helped in passing this exam.
Preparation:
About a month of on and off studying.
Exchange 2010 / Windows 2008 in lab. (On my MacBook Pro)
Exchange Server 2010 Administrator Pocket Consultant
TECHNET.
I'm gone to take another week of studying and take the 70-663 to knockout the track. Then back to my CISSP studying darnit.