The current Prius has that, but the glass breakage sensor is optional. I suspect, but don't know, that it will be the same for the 2010. Tom
There will be no factory installed alarm (though engine immobilizer is standard). However, you can get an accessory installed alarm system at the dealership. Doug Coleman Prius Product Manager Toyota Motor Sales, USA
I'm not sure how much value is in the factory alarm unless it includes a glass break sensor. Any ideas how this will be packaged @ the dealer?
If someone wants the car they will get it..and a window sensor won't stop them. That said, the engine immobilizer is better than nothing at all.
The point is to draw attention - the last thing a thief wants. You're correct though, smash and grab is quick and usually done before anyone can do much about it. Tinted (film) windows would slow the progress just slightly though ;-)
Regarding Gen II: as far as I know, it is (or was) standard. I'm assuming that you meant Gen II, and not Gen III?