It said on the Swedish forum Playstation 3. I'll use googletranslate.
Did you think the rumors of future models of the Playstation 3 would end with advertising of the PS3 Slim? Then it's time to think about, almost immediately after Sony announced the PS3 Slim to Gamescom exhibition came the rumors that another model of it is going. The model is said to have a hard drive at 250GB, while the advertised is a 120GB.
Rumors started after ps3news.com found documents from the FCC (Federal Communications Commission) showing that a 250GB model is really supposed to be launched. In order to be allowed to sell electronic devices in the U.S., namely, the products must be submitted to the FCC for testing. The documents also reveal two models designed for game developers.