The exceptions made recently in the DMCA only make exceptions for Professors and students under certain conditions. Under those conditions, to circumvent the iPhone's default OS or software is still in breach of the Apple EULA which voiding the warrantee could be the least of your worries even...
The Apple store has recently been granting support to those who have jail broken their iPhones under conditions that they restore the phone to it's original default settings. The iPhone is yours, but unfortunately the software is strictly the property of Apple and do not extend to you the freedom to modify, circumvent, or disassemble in anyway.
There is an appeal from Apple to combat these kinds of acts despite what exceptions have been made in the DMCA through a possible patent on surveillance firmware.
http://www.eff.org/deeplinks/2010/08/steve-jobs-watching-you-apple-seeking-patent-0