Opera started out with just part of one floor and seven staff and has expanded to cover most of the building, which means it's an often-confusing realm of corridors, stairwells and a surprising number of office printers. There's plenty to keep the development team happy: the coffee machine was upgraded after complaints that the existing range wasn't good enough, a massage therapist visits weekly, there's an in-office gym and a playroom to keep kids entertained, and staff sometimes volunteer to cook their national cuisine (more than 50 nationalities are represented in the office). Check out the pictures below for a fuller view of the facilities. I can confirm that the bean bags are very comfortable.
Disclosure: Angus Kidman travelled to Oslo as a guest of Opera.