Popular Mechanics took a prototype plug-in 2009 Prius for a short test drive, which might be the first PHEV to market. The Prius they ran around still uses the Prius's current nickel-metal hydride battery packs—a pair, actually, with the charging system jimmied in between them—though Toyota hopes to switch to lithium ion, which are more efficient and smaller (thankfully, since the jiggered NiMh packs leave only two medium suitcases worth of trunk space).
Jibing with a Boston Globe report that Toyota's having problems getting the Li-ion batteries ready, the car might launch as regular hybrid at first, making the jump to plug-in action after the Li-ion tech is good to go. The other possibility is that'll be a plug-in from the start, but with the NiMh pack initially before moving to Li-ion when it's ready. Still, the new, more aggressive EV mode which allows acceleration up to 50mph before jumping to gas is reason enough to want one. [Popular Mechanics]