I'm a Nintendo fan and don't play much of either, but I have played each of them and they have their good and bad points.
I like the 360's controller in terms of buttons (the PS3's shapes confuse me so much D: ) but the PS3 controller is more comfortable.
Live is a paid service while PSN is free, but there's that whole problem with PSN right now.
I like the 360's games a lot better.
Overall, I'd have to choose the 360, simply because I'm more familiar with it since my brother has one.
No, GeoHot and Graf_Chokolo hacked their own console, and published the Private Key.
They never attacked PSN.
It was a group of internet users, which fights against internet censor, and the group is called Anonymous.