I've heard in other places that it's C++ but my programming professor looked at it briefly and thought it was C. Is there anything that uniquely identifies it as one or the other?
The word "class"
At the very beginning, C++ was indeed called "C with Classes" 
Of course, today the differences are a tiny bit greater... still, with a simple program it's hard to spot them.
Here's a link to my blog post about the identity of the Arduino IDE programming language:
http://www.idogendel.com/en/archives/19
Since C++ is a superset of C, does it really matter? The IDE creates a file with a cpp extension, which should give you a clue.
OK that makes more sense. I'm learning java right now in school so I'm too familiar with C and C++.
wcjones:
I'm learning java right now in school
You have my commiserations.
...R
(PS, I'm not a fan of C/C++ either - I just do the minimum I have to)
Lua FTW