While there are dozens of Priuses that have been converted into plug-ins on the roads, there are very few official Toyota plug-in Priuses out there. Why? Because while Toyota has created a plug-in Prius prototype, it won’t be on sale until 2012. But for this week’s episode of GigaOM TV’s Green Overdrive show, we got to take one of the official plug-in Prius prototypes for a drive. It drives about the same as the regular Prius, but has a larger lithium-ion battery, and charges in about three hours. We’re hoping the next-gen version has an even bigger battery and drives on more electric power.