I once had a roll of Kodak 400ISO 35mm that was half shot and left in a camera for two years after I bought a new camera. Then I found the old camera, shot the rest of the roll, and had it developed.
The roll turned out quite normal; I saw no odd color shifts or any other abnormalities (beyond the normal tendency that Kodak film has for washing out colors and turning blue skies gray).
Remember that when storing film, either exposed or raw, HEAT is your biggest enemy. Some professional photographers even keep film in the referigerator, although Kodak says that's only nessecary when the ambient temp goes above 24C (75F). Moisture is also a danger to film, so make sure to store all your film, exposed or raw, in the plastic canisters and in a cool, dry spot.