Yahoo does have a social network. Messenger, gaming, profiles, friends (contacts), and just about everything that FB has. it's just uglier and lacks the simplistic search bar at the top that makes things so much easier.
Email can't be defined as a Social Network in the context of this patent, because they had to define what it constitutes a Social Network to be able to use the term in their text.
But Windows Live Messenger can be defined as a SN, with that definition. I don't know if Yahoo! Messenger could also be included, because I don't use it and I'm not very familiar with it.
I would certainly hope that any IP attorney litigating these patents would be able to argue that email is most definitely not a social network as used in the context of the patent.
