I understand QEMU is a CPU translator, not a "virtualisation solution" like VMware... Basilisk etc are emulators.
* POWER5/6/7
IBM Power Series computers bring their own solution. I think it's called the IBM Hypervisor.
* PowerPC
Mac-on-Linux worked excellently: http://mac-on-linux.sourceforge.net/
I used it to run Mac OS and Mac OS X on Linux.
Sheepshaver was nice: http://sheepshaver.cebix.net/
It ran Mac OS on BeOS.
And then, of course, there was Apple's Classic Environment which allowed running Mac OS 8 or 9 under Mac OS X.
I understand Xen has a PowerPC port as well, but I'm not sure what state it is at.
* Itanium 64
HP offer a solution which can be bought with HP servers. It is a Type-1 (bare metal) hypervisor and hosts HP-UX and Windows Server 2008.
There is also some sort of Parallels product: http://www.parallels.com/solutions/virtualization/itanium/
* NEC SX-8/9
* Cray X2
* BlueGene
Don't know anything about those machines.