Our original builds used it on vmware as I mentioned When buyvm originally opened we were on a very strict budget since Frantech was fully sold out as was our power. The vmware's ran OK unless ther was spikes. The biggest issue we had was vmtools kept crashing/unloading tanking performance. We actually had to have someone on hand 24/7 monitoring for load spikes/etc that would occur all the time.If you are interested in trying out it yourself, any KVM/vmware/XEN(HVM) provider will work.
Like @, said... only provider I've read about that openly said they do it is BuyVM and that is for internal stuff only.
With the recent thread on LET about BuyVM doing it, I guess we have to take their word on it that they are not still doing it on production servers h34r:
We still do OVZ for internal stuff. I don't see a reason to keep big nodes around for compiling kernels/testing kernels when a simple KVM does it all.