About 3 months ago.
Don't get me started on that. The server we're going to use is serving another function for an app that doesn't run on W2K3 yet.
My sysadmin voice says buy a new server, latest & greatest, but the beancounters won't spend the money for 20 BB users.
As long as the BES and Exchange servers will work properly on the different platforms, we'll be OK until we can get the other app upgraded, and move everything to the new OS then.