I have about 15 of those 30W chips. As others have said, they require 30-34V and about an amp of current. Hooking up 12V won't push the chip past it's knee voltage, and no significant amount of current will flow.
Unfortunately, they need LOTS of thermal dissipation (picture a heatskink on a pentium 4 computer), and they also need current regulation to avoid going into thermal runaway due to the positive thermal coefficient. (the hotter they get, the more current they try to pull). Without a heatsink, the chip will hit 150C in just a minute or two and then start self-destructing. With a BIG passive heatsink, you will hit 40C in about 20 minutes and the working life will be diminished. Nothing less than a good heatsink and a fan will keep the light running indefinitely. I am working on a water-cooled project with about 450W worth of these lights. It's a bummer that I've spent 3x as much on cooling as I have the lights themselves, but that's in the nature of the thing.
You can buy current regulating boost converters for pretty cheap (~$10) on fleabay. They will happily convert 12V to the 30V+ needed to drive the light, and if you get a constant-current unit (HIGHLY recommended), it will keep the led from pulling too much power and burning itself out.
It is kind of a bummer that the heatsink and driver cost way more than the chip itself, but once they are setup right, they are BRIGHT.
I have barely functional internet access at the moment otherwise I'd post a bunch of pics. The glow passes very easily through my hand. It is outstandingly bright.
