I've just approved a bitcoin bet on the existence of a such a miner:
mtrlt has a fast LTC GPU minerYou are welcome to place your bets.
You can also PM me if any evidence surfaces either way.
If you change the bet to generic "will a LTC miner capable of running 250 kh/s on an 6990 be proven to exist by March 1st 2012?" and allow anyone (not just CoinHunter or mtrlt) to provide the proof, then it could be a bit more fun.
Sure, but since the bet is already created, my only suggestion to the moderator is to clarify how they will determine whether the conditions are met.
Will Solidcoinites take the challenge?