IBM's history has shown they are not afraid to use their patent library offensively.

http://www-03.ibm.com/press/us/en/pressrelease/21509.wss

http://www.highbeam.com/doc/1P2-5527642.html

http://query.nytimes.com/gst/fullpage.html?res=9A0DE3DF133CF...

http://www.engadget.com/2007/12/06/ibm-tries-to-stop-asus-im...

And that was just from a 2 minute Google search.

Notice settlements are called "cross licensing" but only have money going in one direction - towards IBM.