iFever

On the eve of the iPhone launch, WIRED has a couple of hints how to try and get out of your contract if you're with another carrier.

Pawn it off
Don’t want your contract anymore? Find someone who does. Websites like Celltradeusa.com specialize in connecting thousands of people together for the express purpose of transferring the financial responsibilities of cell contracts from one person to another. As long as the recipient meets the minimum qualifications (credit check, etc.) you can transfer the plan over without getting hit with the early termination fee.
Odds of success: 2-to-1

Get out while you still can
If you just signed up for service, you typically have 14 days to drop it -- 30 days with some carriers. A simple call to customer service cancels your plan. All you may have to do is pay a prorated amount for the service you’ve already used.
Odds of success: 3-to-1

Move to the boonies
It's pretty simple to register a change of address with most carriers. Change your address to an area your cell carrier doesn't have service, then call and complain about not getting reception. Contractually, if a service provider can’t offer access in a given area, the contract is null and void.
Odds of success: 5-to-2

Military service
If you’re already in the armed forces, deployment overseas usually means you’re free and clear to end your contract early -- without any financial obligation.
Odds of success: 6-to-1

Read the fine print
The wee print in your bill’s Terms of Service? Read it closely. Providers frequently make small changes to you plan -- an increase in the number of text messages here, a few more night and weekend minutes there. It doesn’t matter if these alterations benefit you -- they automatically void the contract and give you as much as 30 days to get out.
Odds of success: 8-to-3

Demand to see the paperwork
Did you sign a contract in the store? Ask the carrier to come up with a hard copy of this legally binding document. If the provider can’t come up with a physical copy, then you’re free to go. Paper gets lost, you might have forgotten to sign and sales reps are often too busy or lazy to file the paperwork.
Odds of success: 10-to-1

Abuse the system
Cell-phone service providers usually have roaming agreements with other carriers where they don’t offer reception. Roaming areas can often be close, sometimes the next county over. Chances are you have a friend with a house in one of these roaming areas. Check a service map to find out. Then take your phone over on Friday night and as soon your Unlimited Nights and Weekends start, call POPCORN, and leave the phone on. Roaming is usually free to the customer but costs the carrier dough. They’ll practically beg you to leave when you call to cancel the contract.
Odds of success: 20-to-1

Fake your own death
Have a friend or colleague work up a good set of tears and call in on your behalf claiming that you’ve shuffled from this mortal coil. Report something feasible yet horrible, e.g., "He … he was just ripped to shreds by that farm machinery." The contract will be terminated because you are. Note: This is wholly unethical and probably illegal.
Odds of success: 50-to-1