Yes, it appears that the North American Prius fuel tank system is needlessly complex. Since Toyota installed a different system for Highlander Hybrid and Camry Hybrid, their engineers presumably reached the conclusion that the bladder design should not be adopted for new models.
i agree with diamond, while the prius is an amazing car, the fuel tank is a "pink elephant". Good to hear the next gen will probably forgo the use of the bladder IF the car states it hold's 12 g of fuel, it should hold roughtly 12 gal of fuel, no more no less. I plan to trade up in late 2010 for a 2011 prius. Unless the volt is better, if it even comes out.