Recent news about Twitter being used as a Botnet Command Center sounds so natural. At the risk of sounding like a second-guess, it appears like the most simple control path (barring only the frequent down times prone with Twitter service).
Couple that with the Opera Unite concepts and you have a good mobile threat vector. Yes, the Unite technology is also still being stabilized. But, that should not stop us from predicting some threat scenarios we are about to encounter in the near future (“near” as against the usual Science-Fiction measure of future).
I have similar feelings on Facebook, but have never had the patience to hover there long enough to give more thought.