Schwarzenegger Confirms 'Terminator 5' Involvement

Although this has yet to be officially confirmed, according to the original Terminator himself, Arnold Schwarzenegger, he will be in Terminator 5 -- which is currently being written by Patrick Lussier and Laeta Kalogridis.
Briefly: our man Patrick Dane is down at the London junket for The Last Stand and he reports back, in short, that Arnold Schwarzenegger will be appearing in the next Terminator movie. Arnold said so himself.
We currently await an official announcement.

Source: Bleeding Cool