One of the issues with PhysX is a lack of good game support. There have been a few games that have had minimal support but most of that support was, quite honestly cheesy.
Now nVidia is really pushing the GPGPU power of its Graphics cards in combination with PhysX and driving the industry to release games with real support. One of these games is the upcoming Cryostasis: Sleep of Reason.
This game is going to be a first person horror survival game that will leverage a large amount of fluid simulation as to enhance the feel of being in a frozen environment. To check Cryostasis out for yourself you can now grab the DX10 tech Demo.
PCGames Hardware has more Here.
The Cryostasis tech demo primarily demonstrates water effects which the developers paid a lot of attention to. Thereby Nvidia's Physx and DirectX 10 are used, so that owners of a modern Geforce card (Geforce 8 or better) receive a performance benefit. The demo can be downloaded at Gamershell for example.