would it be possible to detect such an attack and "vote the attacker out of the network"?
just random thoughts... like upgrading to a client that limits haspower within a certain region or ip-range...
The first point would be wonderful if feasible.
Regarding the second point, take into consideration that the whole paradigm of security/honesty of Bitcoin is based on brute hashing power. Reducing hashing power means getting weaker to attacks. What you say would require changing the whole security paradigm of Bitcoin. Not saying its not possible, but would need some of out of the box thinking IMO. But then again, I am just a newbie here.