I agree with Kaliyan, because the only way that implementers can test (and learn by the way), probe several designs is with the 32 versions only.
I think that is very unfair that Exchange Team doesn't have a 32 bits version for Testing Purpouses only.
I'm implementing Exchange 2007 right now, but I don't have the posibility to test Exchange 2010 only because isn't available a 32bits version of Exchange 2010. Damn this is to bad, because How I suppouse that I'm going to implement a Step by Step transition from Exchange 2007 to Exchange 2010 if I don't have a 64bits machine for testing purpouses.
Exchange Team Hope that you reconsider the release of a 32bits version only for testing pourpouses in the same manner that you did with Exchange 2007, that was really very helpfully.