The exemption also specifically states that the exemption only applies to "wireless telephone handset" ... "computer software, in the form of firmware or software", where the purpose of the hack would be to enable the lawfully obtained device to operate on a different network than the one it was sold as restricted to. (Designated class C). Class B states that it is legal to build (and distribute?) programs designed for wireless telephone handsets that are legally obtained in their own right (don't reuse code that say Apple developed), but again it is restricted to "Wireless telephone handsets ... connected to a wireless ... network"
Using the letter of the law, PS3 jailbreaking is not covered under those exemptions. The only exemptions relating to video games are to controlled DRM works where a hacker wishes to research security vulnerabilities, but the "information derived from the security testing is used or maintained in a manner that does not facilitate copyright infringement". Sony might have a decent case against GeoHot based on this, since he released the keys that enable people to sign custom code that may act as a frontloader to bypass DRM checks for illegally obtained copyrighted code.
Us hackers might consider the differences between a PS3 and an iPhone negligible enough that hacking either is logically the same task, but the DCMA states that they are two separate beasts and hacking one is entirely different than hacking the other. Unfortunately, people need to follow the letter of the law in order to stay out of these kinds of legal challenges, but these legal challenges are also what help craft the law to be fair. I just wish that GeoHot had a better chance at winning this. He should have been thinking about how to cover his ass a long time ago.
DCMA Exemption source [PDF]: http://www.wired.com/images_blogs/threatlevel/2010/07/dmcaex...