re: Keith Smith 1
"Having an actual full blown OS underneath your HV adds a bunch of flexability to your mix"
In what sense? Surely it is better to have a type-1 hypervisor that talks directly to the hardware without needing an OS to run it (the hypervisor)? In terms of flexibility, you're type-2 hypervisor (the one you describe) would need to have drivers embedded in the host OS to run the hardware akin to how hyper-v's parent partition needs them.
I don't see how this can be more flexible than a type-1 unless you're talking about a situation whereby the hardware you want to run the type-1 isn't on the HCL. If it isn't then you shouldn't be trying to use that piece of hardware.
Performance on a hosted hypervisor will be pants when compared to bare-metal, you won't be able to scale as high as bare metal, and you have a host OS "translating" between the hypervisor and the physical devises.
VMware are market leaders in this game, ergo, people like to take pot shots at them. VirtualBox will NEVER eat VMware for breakfast. Solaris was always better than Windows but did Solaris eat it for breakfast? Of course not.
With regards to Hyper-V, it runs Novell (Suse) Linux and Windows. That's pretty much it. Microsoft claim they will run more Linux flavours but I can't see it really happening.
VMware runs by far and away the MOST Operating Systems out there, right down to DOS IIRC.
Not sure about OS2 though ;)