I had heard rumors of this at Tech-Ed… Maybe we need to move all the VMs off of our 64bit ESX machine and start messing with 64 Windows to be ready…… From what I have read the 64 bit version of Exchange will be an absolute powerhouse. Exchange has always been able to scale up to massive proportions in the past, I can’t even begin to fathom how many users/messages a 64 bit version would be able to push out. Especially with today’s new hardware!
Breaking news: Exchange 12 will be 64-bit only. I have a lot more detail to post on this, but they're about to close the forward boarding door-- more when I land in Cincinnati in an hour or so. Here's a link to the umbrella press release from IT Forum.