Moviehole talked to Transformers star Rachael Taylor, who explained why you won’t see her in the sequel:
“I wasn’t contracted for a sequel anyway, but I also think it would be pretty ridiculous for my character just to show up and say ‘We’ve got some more computers to play with!’.
More importantly, I don’t think I’d wanna do it to be honest, and not for any particular reason other than the fact that I’ve done it. I’m just drawn to doing different things. It was the same when I went to the U.S, I didn’t want to do TV, because I’d done it. I want to be able to mix it up all the time.”
Tranformers 2 is scheduled for a June 26, 2009 release.
Source: Moviehole