Hello gentlemen.
Breivik won't be getting out of jail ever, just so you know. The max sentence is indeed 21 years, but after that he will be subjected to "confinement" on grounds that he'll be a danger to society, and that the society will be a danger to him.
However, jail in Norway is more like staying at a mid-range hotel, complete with internet, TV, games, education, health care, and so on. So Breivik's punishment won't even begin to compare to his crime anyway.
But at least we all get to laugh at him for the following weeks, during the clown circus we call a trial. Not sure if you heard, but he broke down crying once a couple of days ago - when they showed his homemade crappy propaganda movie in court. Apparently the pride was too much for him.