CRN | 64-Bit Exchange Server | Microsoft Making Exchange 12 64-bit Only Sharply Criticized: "'Sixty-four bit is definitely coming on, and as people move forward to new systems, they'll buy 64-bit servers,' said Pawlack. 'But we're not there yet. I think upgrades and migrations [to Exchange 12] are going to be very slow.'
Last week, Microsoft announced that Exchange 12 -- which should release sometime in the first half of 2007 -- will be exclusively 64-bit. By Microsoft's account, it made the decision because of the performance gains that 64-bit offered over 32-bit. "
I disagree -- I think it was a reasonable and timely move on Microsoft's part, and I also think they thought through the migration issues. Exchange 12 is a 2007 release -- x64 servers will be the norm by then.