Xen domain creation will fail due to memory not being the right size. The logs show that memory is always of size 0. This is due to ParaVirtGuest.py and possibly FullVirtGuest.py using memory * 1024 as the argument. xenguest-install takes memory in, and just passes it off to the correct xeninst module, but without converting it to an int fist. This causes the memory to be 0, string * int.
Fixed this in hg today, will be in the next build of xenguest-install