In 2005, California started issuing special "high-occupancy vehicle" stickers to people with Priuses and other hybrids. These stickers allowed them to legally use the faster carpool lanes any time, even if they were driving solo. There were 85,000 of these stickers issued and they were extremely popular. They ran out in 2007, but the the existing ones still work.
Not for long, though. Governor Schwarzenegger just signed a bill that changes things. As of December 31, hybrid drivers with the yellow HOV stickers will be stripped of their special privileges. Drivers with the extra-special white HOV stickers (which are reserved for Teslas and other super-clean cars; see the picture) will get to keep their carpool lane privileges, though. There's no limit (yet) to how many of the white stickers will be issued.
Apparently some Prius owners are pretty upset. But as a Prius driver who managed to get a set of these stickers myself, I'm totally behind this change. The stickers did their job. They made hybrids substantially more attractive when it mattered. But Prius sales are doing fine now and besides, a Prius isn't that much cleaner than a standard car anyway.
The Nissan Leaf and the Chevy Volt are about to hit the market and we now need to provide incentives for people to get them. The only thing I'm bummed about is that the resale value of my car just dropped by a few thousand dollars.