According to this report http://www.businessweek.com/magazine/the-biggest-ip-war-chests-08042011-gfx.html RIM has the biggest I.P. war chest in mobile (more than Microsoft or even Nokia). With a current market cap of about 12 billion US$ it would be "only" 3 times more expensive than the Nortel patents but would bring much more to the table than just patents (RIM is stil pretty profitable and could help Google significantly in the attempt to gain more corporate clients).