Facebook already has a social network. Google already has a social network. Apple's probably not interested in running one post-Ping. Who else is going to purchase them at a price their investors - who've sunk over a billion in VC $ - wouldn't balk at?
Have they really had over a billion in investment capital? I realize they may have had investment rounds valuing the company at 1bil+, that doesn't mean they were given a billion dollars.
