As supposed, Deus Ex Human Revolution should work with Nvidia 320M as stated by Feral at their Facebook :
Many unsupported cards will run the game, but with a bit of stutter, so we understand that you’d rather see for yourself.
If you meet the other specs, the game will work on that card. The only reason we don’t “officially” support it is that there is still a little bit of stutter, and we want all officially supported machines to have perfect performance.
The game is available through the Mac App Store (39,99 euros, 15 GB).