To clarify things, what VMWare Product / Version / HostOS / GuestOS are people talking about here? It is quite possible that certain combinations of HostOS + GuestOS could cause problems with IS, especially if you’re running versions of GuestOS / HostOS not explicitly supported by VMWare (and by extension, versions of GuestOS not supported by IS/Broker).
In the hands of inexperienced sysadmins, I can see how VMWare would destablize IS running on it, especially transient problems (network, I/O, Disk, # of processes, somebody running Virus Scanner on your host Windows, whatnot). VMWare ESX would probably be much less prone to these problems, but I haven’t played with that at all.
But, that’s not to say I don’t like VMWare with IS/Broker. Since there are many combinations of Product/Version/HostOS/GuestOS, with even more coming (i.e. IS 6.5 SP1 supporting Solaris 10 on AMD64), I think wM is wise not to officially support VMWare. It’d be a support nightmare. But for people who know what they’re doing (like Sonam’s configuration), they’re a great tool for the sysadmins.