How to attain a WPA2 password if you're already connected to the

Hey,

In my school, every single kid gets a tablet PC, so we're all connected to the wifi WPA2 network. However, I have an iPhone, and I don't want to have to pull out my tablet every single time to check my email, listen to the radio, and so forth (I live in Switzerland, have limited data, and @ my school I can only get edge...so wifi is pretty much of choice here)

Does anyone know of any method I can utilize to gain access to the WPA2 code? I want it to be non-intrusive...hopefully I can retrieve it from my computer itself? I'm pretty good with computers, built this one...so if it's complicated, I'm up for it.

Anyhow, thanks for the tips.