Some people don't seem to believe that it's okay to use the code I post. If you want to take my particle generator and throw it up on the App Store, more power to you, but you have to support it. Seriously, you can use it for anything you want. The only thing I ask is that you don't replace my name in the comments. You can feel free to add your name if you make changes or additions, just don't take my name off, and just about anything you want to do with the code is fine by me.
If you do do something cool with it, drop me an e-mail, I'd love to see what you come up with.