If you remember our first grope of the DS-Xtreme, it's a DS-sized cartridge that goes into your Nintendo DS that lets you run homebrew apps on it. If the homebrew apps you decide to run included actual DS games, so be it. Now the DS-X cartridge has been upgraded to 2GB from 512MB.
One of the main complaints we've had with the unit is its lack of space, forcing us to swap in and out games whenever we had to take a long dump. Now, for the same price ($129), you can hold four times as many games. But the original 512MB version will get a price cut, so grab that one if you don't care about the space.