On my way to work today, I wrote a "particle engine" in Python on my iPhone. Particle engine is a fairly generous term (it's 90 lines) but hey it's plugged in to the accelerometer!
I used the Pythonista particle demo as an example but I didn't borrow its implementation as you'll see. I use a simple ring buffer for particles and emit using a simple physics model where the accelerometer value is the force of gravity (F=ma anyone?). Take a peek-- a full xcode project is here: