Michael Capozzi claims he has found a way to unlock the iPhone 4S without using any hardware or software. This video shows a demonstration of his method. It has not been confirmed by us or any third party yet.
Update: some people have confirmed this method works. However, you will need to repeat the process in case you reset the iPhone.
Update 2: Other people are reporting that it's not working for them. There are mixed results, so proceed with caution.
Note: Apparently, this works with AT&T's iPhone 4S, iPhone 4 and iPhone 3GS. You will need to cut the T-Mobile SIM card so it fits into the Micro-SIM card slot in the iPhone 4S. There are several devices to do this accurately available online. Like in past times, proceed at your own risk. While the method appears to work, it has not been tested by us yet.