Microsoft says they’ll support Exchange on virtualization platforms that have been validated through their Microsoft Server Virtualization Validation Program (SVVP). Shortly after this release, some noticed that the other big player, VMWare, was not in the program. But shortly after, Microsoft said VMware has now signed on to the SVVP program. Microsoft is certainly excited to add VMware to the program, recognizing the value this provides to Microsoft customers.
This announcement has been long awaited. Many companies have either gone ahead and virtualized Exchange (generally on VMWare), or held off while waiting for the statement from Microsoft.
I suspect now that we’ll see a large transition to 2007, now that this barrier has been dealt with.