A discussion on the SF board has left me wondering about this. Of course, there are hundreds of distinct, ethnic cuisines in India, but in California you tend to see Indian food labeled as either North or South Indian. I always associated South Indian food with chaat, fried finger foods and dosas and North Indian food with curry. I've also noticed that in California most sit down Indian restaurants are North Indian, South Indian restaurants tend to be cheaper and order at the counter style.
I've never been able to come up with a good way to categorize dishes as Southern or Northern and I've never felt completely comfortable using either term.
I'm sure there are some folks out there who are far more informed than I am on the subject. Please enlighten me.