A new live wallpaper (LWP) app has been released on the Market. LWPs may be a dime a dozen, but this one is definitely worth a look:
From what I can tell, there is no actual relation to NVIDIA/Ageia's PhysX engine, other than a focus on physics (who would’ve guessed?). The effect is quite cool though - the particles move based on how you’re holding the phone, and can be set to act in various manners. Very nifty.
There are a variety of color combinations available (“Deep Blue” is below), and you can opt to change how the particles act.