Turns out that Linda Hamilton has already recorded her voice overs for, “Terminator: Salvation”. You will hear her voice overs in the opening intro of the film, just like “T2: Judgement Day”.

More on it here:

http://chud.com/articles/articles/18541/1/IT039S-OFFICIAL-LINDA-HAMILTON-IS-IN-TERMINATOR-SALVATION/Page1.html

Kev