Sony releases the firmware 1.70 update for the PS3 is supposed to improve game play performance and adds rumble support for PS2 games and controllers.

Rumble is missing in the PS3 SIXAXIS controller. The new firmware lets you at least enjoy force feedback on Playstation 2 games if you own a USB rumble controller that is supported. You cannot connect a PS2 controller to the Playstation 3 as it does not support the interface and only accepts USB controllers.

Sony lists only the following few compatible force feedback controllers: Streetcar GO! Controller TYPE2, Streetcar GO! Shinkansen private controller, Hori Flight stick 2 and GT-FORCE Pro.
These are mostly Japanese market only controllers. Not sure how many of them are actually out there. Additionally you need to have a PS2 game that actually supports these controllers. The Hori Flight Stick 2 is listed on Play-Asia but out of stock.

The other new feature allows you to store PSP game data on the PS3 HDD.
Via the Japanese PS3 Firmware page (Japanese).