Since Tesla mentioned plans to do "REEVs", they need to keep an eye on the Hybrid Consorium.
Battery makers like A123, eMotor makers like Raser, and transmission makers like NexxtDrive are members.
"Dual Mode Hybrids—PHEVs
A Dual mode hybrid can drive around town in all electric mode, and automatically switch to hybrid mode for longer distances. This allows most drivers to operate most of the time without burning gas. A dual mode hybrid can run in zero mode much of the time on clean renewable electric energy for just about 50 cents per equivalent gallon. The Consortium will coordinate the development of the advanced technology needed for this kind of car and incorporate this technology into cost effective PHEV designs. The Consortium will then work with major automakers to build prototype PHEVs that can achieve 100-200 total mpg petroleum economy by driving its first 20 – 50 miles in all electric zero emission mode."
So, is there a difference between a "REEV" and a "Dual Mode PHEV"?