If anyone could identify what this part is (and its function), I would appreciate it.

When I installed my Carbonio Intake, I had to unclip that from the stock airbox, but I don't know what it is. The instructions didn't address that part, I check for ya. Sorry. [:@]

I believe it is the EVAP purge valve..

Thats exactly what it is. Evaporitive emissions purge valve. It takes fuel vapors from the gas tank and burns them in the engine. Thats the valve that controls how much vapor gets released to the engine. The epa gets kinda upset if gas fumes get let out into the atomosphere, so screwing with that system will get you that big fat check engine lite.