The software patent end of the industry is a house of cards. Currently it only holds up because everyone plays along. In order to sustain the house of cards all the major players have to cross license all of their patent portfolios. No one really even knows which patents they are violating, or being violated at any time.
You only see small skirmishes play out, like Motorola vs Apple, major ones are always settled. The major players use this cross licensing to try and keep small and medium sized companies from coming into their space. Once you generate enough revenue to put up a good fight, they have to let you in 'the club'. Facebook crossed that threshold. FB will now cross license with all the other players.
A system initially designed to foster innovation is now a detriment. The mass cross licensing of patents should be considered in anit-trust light. It allows the major players to share ip, while blocking the others and keep their prices artificially high as a result. No different than direct collusion. The system should be unwound.