Well, no one but DELL and their monkeys can get it because DELL cut a back door deal with nVidia to get it before anyone else. So if you want it you need to pay for DELL's XPS system.
You can upgrade in the future to the 512 MB card, but I'm sure the next latest and greatest will be out by then anyway making the 512 MB a non-event... at least that's DELL's plan I'm sure. When is the x1900 getting to laptops!