Not officially supported, but I have been running 2 BES servers on Microsoft Virtual Server 2005 for about a year now with no issues. For performance reasons (meaning only so much RAM that can be allocated from the host server), we have moved the database to SQL Server.
We're running a 150 user production BES server on VMWare. Have been for about 6 months now with no issues what-so-ever.
Runs very smooth and is quite responsive. Actually, I run BOTH BES and METAmessage (PIN Archiving and Auto Updating software for the Blackberry) on the same VMWare machine with no problems.
I have my test 4.1 BES on VM ware. Only reason it wouldn't keep it there is that when MDS, attachments, IM and everything else is running, it is quite memory intensive. When I move my 4.1 to production with ~400 people I'm going to throw 4GB of RAM at it. 4GB on a VMware guest defeats the purpose in my book.
Is that conjecture or based on any published information.
BTW - RIM runs some internal BES on VMWare...
No it is based on personal experience. I believe there is documentation pertaing to Domino and VMWare though. I am a big fan of VMWare but I do not believe it should be used for everything.