There seems to so much hype about virtualization. I can buy a basic server for about $3000 - complete installed - one time cost. My VMware servers are technically less expensive but require more ongoing care and feeding. Assuming both are equal in support of real time applications, which is a real leap as well - why bother putting UC servers on a virtual machine. Makes no sense to me.
Matt - Microsoft OCS doesn't support virtualized implementations (as a solution - only some non real time server roles can be virtualized).
VIrtualization makes a lot sense from redundancy environment because two virtual environments can provide redundancy on the same or different virtual clusters.
VIrtualization offers huge benefits around resource management - don't think of it as server savings. By virtualizing your UC server, you can add/subtract resources (processor, memory, and storage) easily without downtime. You can also backup (replicate) environments with additional virtual (or real) servers at the same or a remote site. Don't think of it as server savings - it is part of voice/data convergence - the operational level.
One of the key benefits of virtualization is to reduce hard servers. But the goal should be to reduce overall servers (hard and soft) - since OCS requires so many servers it doesn't fit well into a virtualization conversation. Anyone looking to reduce servers should be looking at simple appliances like the ShoreTel products. Yes, appliances can't be virtualized, but they are a lot less work and meet the objectives of virtualization projects with a lot less effort and money.
Tom, your post doesn't make sense. "meet the objectives of virtualization products with appliances that can't be virtualized!"
You have tangible benefits like server reduction, rack space, power, and cooling as well as the benefits Dave pointed out with flexible deloyment, backups, snapshots, labs, upgrades, etc...