As discussed on the 'New forum software' board:
I've thought about that before, but I think that there might be legal problems with that. It might make the forum a "money transmitter".
AFAIK Theymos didn't specifically comment about using ChangeTip itself though (to avoid the money transmitter issue)
It'd be nice to get a solid answer if there's any truth to the money transmitter theory. But yeah clearly a third party solution would not be effected