If we're going to talk about obligations... I seem to recall that Microsoft and Apple had made some promises with respect to the Nortel patents they bought (triggered by a DoJ investigation).

Of course, somehow the patent troll they set up:

http://www.wired.com/wiredenterprise/2012/05/rockstar/all/

doesn't have the same obligations, but that still leaves Microsoft's and Apple's hands clean, right?