wow except for roteague, you guys really need to do your research... the gm two mode hyrbids may have 4 fixed gear ratios but combined with the electric motors this creates an evt (electrically variable transmission). This basically allows it to have an infinite number of gear ratios between two fixed points.
"EVT's are capable of continuously modulating output/input speed ratios like mechanical CVT's, but offer the distinct difference and benefit of being able to also apportion power from two different sources to one output." -Wikipedia
There is a whole section under transmissions at wikipedia about evt's... check it out
http://en.wikipedia.org/wiki/Transmission_(mechanics)