Since the Prius and whole Hybrid thing is geared toward city and short-trip/stop-n-go driving for economy, this gizmo makes sense when applied to avert subsequent cold-starts.
My bad! You're right about Cali. You got me interested though; here is how they (Toyota) are going do their warranties for the new hybrid camrysverbatim from) 2007 Camry Hybrid Specifications
8 year/100,00 mile hybrid related component coverage
15 year/150,000 mile hybrid related component coverage (applicable states are: CA, MA, NY, NJ, VT, CT, ME, NH and RI) with the exception of the hybrid battery. The hybrid battery is warranted for 10 years/150,000 miles.
(it's at the end of the document if you are looking for it)
Do you think the thermos trick would be considered part of the "hybrid-related" components?