PS3 is only really safe from piracy because of the Blu-Ray format which prohibits making cheap copies.
What if it was to ever be hacked in such a way that means games could be played off a hard drive? Blu-ray doesn't mean a single thing when it comes to preventing piracy. Besides which, BD writers can be found for £150 and the discs for £7 or so - not really that extortionate anymore.
Anyway, I hope they don't go with serials. Although it's not really that much hassle, it sort of defeats the purpose of being able to pop a game in and being able to play straight away. Granted, this is the same argument used for console games with hard drive installs (which incidently I think is a pretty good move, it should just be optional) but as already mentioned, it will cause problems for the second hand market. Although PC games are traded, it's nowhere near as big as it is with console games.
Anyway I don't reckon it'll happen simply because piracy isn't as big of a problem for consoles as it is for PC. Yes, it does happen on 360 and Wii but a PC doesn't require a hardware modification to be able to play pirated software so it's far easier.
If you're not a complete retard you'll never be caught.
Nobody really knows what they check for - it's all speculation. They'll pull more checks out at some stage.