You are right about the mini B USB connection, though the problem is that the connector on the "official" cable juts outward a bit further than the USB mini B standard calls for. The connector leads may or may not actually connect properly to the PS3 controller's leads.
MotioninJoy
Go to the above site and download the latest driver and be sure to read how to properly install the drivers. This driver supports rumble and can even connect your DS3 via bluetooth. Not every bluetooth dongle works, mind you, so be sure to check the forums and comments sections there.
Um, maybe?:heh:
You might have to force it a bit to make it work.