There's a rumor going around that in the wake of the PS3 root key hack perpetrated by George Hotz (among others), Sony is considering implementing the use of "registration keys" for its games. Nothing is confirmed yet, and Sony has said they are simply "looking at options".
Now to be clear, I fully support the rights of any developer/publisher to attempt to prevent the piracy of their software in any way they deem effective. And frankly, as a long-time PC gamer, I don't see the big deal with serial keys. I've been entering serial keys for my PC games for over a decade.
With that said, I've also been seeing serial keys hacked and cracked for over a decade as well. While I'm sure that can be a deterrent to some, and that there are some serial key systems out there that are effective, I'm not not sure that they're really the answer Sony should be looking for here. They certainly haven't helped protect the PC game industry from piracy.
The problem with protecting software in this day and age, however, is that it seems most of the most effective methods of preventing piracy are the methods that can also cause a larger inconvenience to the paying customer.
While I fully support the developer's right to try and protect their business, I also fully support the consumer's individual right to decide what sort of DRM crosses the line for them in terms of privacy and/or convenience.
I think it would be a real shame if the root key hack, or Sony's response to it (whatever it ends up being) wound up negatively effecting their business considering the PS3 only recently starting becoming profitable for them. They're in a very difficult position, wherein they cannot simply take no action and say "it's ok if you pirate our games", but will likely face community backlash if they try to implement new DRM.