Oh ok, i'm not up-to-date with the wii scene tbh so i just assumed - thanks for informing meSponsored Links
Obvs there's a dreamcast emu in the works, and a port of pcsx2 - that is mainly down to these being pre-existing projects which have been around for years!
However a wii emu/gamecube emu would probably be a while away - noone has tried to emu the wii before AFAIK and the gamecube (dolphin) emu is designed for the wii and would need alot of porting done to reach playability on the ps3.
Xbox is unlikely but not impossible.
Xbox360 is highly improbable - emulation is a very involved process and even with the raw power of the ps3 it is highly, HIGHLY improbable that anyone would be able to create the emulation process of a 360 which is end-user acceptable for playability anytime soon (within 2 to 3 years).