Every time I go to training, somebody asks this question. What they are telling us at the Toyota Centers is that they have a team of engineers working on the new design, but it's a backseat project. Supposedly, the grab engineers off of the Celica project whenever they need some to develop a new model. If you check this page:
http://www.toyota.com/concept-vehicles/index.html
The FT-HS is what the Toyota guys are telling us is the current concept Celica. I don't know anything more solid then that, though.