I've looked before. The Lexus ES330 has one that's awfully close, but as I recall, it's still not EXACTLY the same. The actual mounting points for the airbag are not the same. Externally, it looks like the same shape, but internally, it's different. But it'd be a sweet swap, airbag and all:
I assume that all airbag wiring is essentially the same. It's just a 2-wire connection with the little harness plug. But if you get in a wreck and for some reason, the incorrect airbag that's in the car (say it's a Lexus airbag) doesn't go off, is there an insurance or legal issue? I don't know...