Does anyone know if Terminator: The Sarah Connor Chronicles will be going on to a 3rd season?

Probably not. The ratings have been low, and are even worse since moving to Fridays. It's also an expensive show to produce. Odds of it being canceled are very high. The only hope, and it's a slim one, is that the new movie does really well in the box office. If it does, they might renew TSCC for a half season to see if they can capitalize on the popularity of the movie. It's a long shot, though.