Depends on the type of game. For the "big" games, certainly C and C++ as that's what the big engines and middleware are written in (e.g., Gamebryo, Unreal, id tech, FMOD Sound System, the RAD Game tools stuff etc.).
Python is used in some games as a scripting language (for game logic, missions, sometimes AI), but there is also LUA and possibly many others, but python certainly is used here.
For "casual" games you might also consider Flash/ActionScript (Browser Games are also games, and it's a big market) or C#/XNA (although that did not really take off).
If you want to develop games for the iPhone, Objective-C is your best bet as the alternatives (Flash and MonoTouch) have yet to prove themselves.
What do you actually want to do in game development? Do you want to work on a Graphics engine? Or Sound? AI? Game Logic?