Tech Question for the Hive Mind

[faustfatale]

My very basic cellphone is starting to crap out on me, and I figure it's time to upgrade to something that allows me to email and tweet on the fly without resorting to the infuriating standard telephone keypad method of alphanumeric conversion. Of course, I want an iPhone so I can be cool like ladyeuthanasia and docbrite, but would really rather not be forced to break my contract and switch phone companies. (I'm currently with Sprint.)

Suggestions? Warnings?