Sony officially introduced accessories for the Sony PS3.

We all know already the wireless Sony PS3 controller now known as SIXAXIS (CECHZC1J). If you need a second one it puts you back 5,000 Yen (~$42) in Japan. This is actually an ok price, unless you want to use all 7 available controller ports. Then it sums up to 250 Bucks (for 6 controllers).

Additionally Sony introduced the memory card adapter CECHZM1J, which sells for 1,500 Yen (~$13) and the so called BD remote control (CECHZR1J) selling for 3,600 Yen (~$31).

The memory card adapter lets you use PS2 cards on the PS3.

The BD remote works also via Bluetooth and lets you control the Blu-ray disc player on the PS3. The PS3 controller and the memory card adapter ship at launch time in Japan. The BD remote control comes on December 7th.
There are no details yet for the Sony PS3 accessories for the US.
More details in this Sony press-release (Japanese). More Playstation 3 News.