Toyota has its mind set on developing more cars under the Prius name.The 1st one will be a larger Minivan like version of the current Prius for 2011.
At the end of 2011, we will see this compact Hybrid powered by a smaller 1.5 Liter engine.
Gas mileage should be even better than the "regular sized" Prius.
Expect at least 65MPG.
It will compete more directly with the upcoming Hybrid version of the Honda Fit.
A sporty coupe is also in the works.
Source;
http://www.burlappcars.com/2010/05/2012-sub-prius-toyota-hybrid.html