We run around 400 VMs across 44 (big scary) servers and I find that VMware only exists as a cop out for bad planning and bad architecture, albeit more cost effective than fixing it. It also shoots you periodically like 2Tb LUN size on our vSphere meaning we had to introduce mega-frigs to breach a 2Tb filesystem like NTFS links and sharding. 2Tb isn't much.
I think most enterprises are using as a big sticky plaster.
It has a few really nice use cases (legacy one-off winxp servers running software from defunct vendors, rhel3 host for old image software aquired by adobe and shelved? perfect in both cases), but the other stuff I've seen it put to has been horrible. jboss on linux on hundreds of hosts converted into a big blob of jvms running in vms...there's no point in giving up that much hardware when the number and config of the servers remains so consistent, and thanks to balloon memory vmware keeps stealing ram from the vms. it's a lot of money to solve the "I need a virtual kvm" problem(?)
I think most enterprises are using as a big sticky plaster.