After having my imac for a whole week now and testing out many games and benchmarks. I can say that the 6970m is a beast.
Two worlds 2 for steam on mac looks amazing! Like really amazing. Plays in full settings with all special effects enabled at 2560 x 1440 smooth as butter. If you like oblivion, you may like two worlds 2. The story is hokey as all get out and the voice acting is somewhat laughable but it seems to not take itself that seriously. It is jaw dropping and quite addictive to level up your character and play the 300 quests in the game. 70 hours of entertainment for $49.99 is a good deal considering going to the movies costs $13 in canada and that is only for 2 hours of entertainment.
Portal 2 looks and runs smooth as well and I have run the unigene demos tropico, sanctuary and heaven. The unigene demos all have around 33 frames per second in the benchmark at 2560 x 1440 with all effects enabled except aa.
All in all I feel that the 6970m is a formidable gaming machine and I am extremely happy with my purchase. I get to enjoy the world of mac while also playing a game here and there with great quality in boot camp.
Downloading the witcher 2 now!!