It looks like NEC has now bought A123. It also appears you can buy AMP20 cells online now. I wasn't aware of this until today. They are very pricey at $70 each though.
A123 Systems Cells and Battery Modules
They also have some B-grade cells for sale that look like they'd be fun to play with. They're cylindrical 3.3V / 2.2Ah for $4.50 each (min order qty 10). These little suckers can handle a CONTINUOUS 70A DISCHARGE! and 120A burst! WOW. These would make a nice small starting battery for something (just make sure your car doesn't sap em dry between driving). They weigh .15 lbs each! Of course they are B grade, so they probably don't fully live up to those specs, but that is still a nice battery.
I'm tempted to try these out on my motorcycle... Say I did a 2p (2 cells in parallel) pack, the starting battery would weigh in at 1.5 lbs haha, silly light.