BuddyPress.org

I wouldn’t be too worried about this. Any software (inc. wordpress) is filled with functionality that has been patented before one way or another (and the facebook news feed patent includes many elements that have been patented by other companies before). Most of these patents have so much prior art that they would never hold up in court. If wordpress core and plugin devs had to check for existing patents for every single function they added wordpress development simply woudn’t be possible and grind to a halt.

A second issue is that software patents aren’t valid outside of the US, so if you’re really paranoid about this kind of thing you can always host your site in Europe.