Apparently, it provides the following additional functionality:
- Enter Flash Exposure Compensation using SET button
- SET button function when shooting
- Shutter release w/o CF card
- Flash sync speed in Av mode
- RAW+JPEG rec. Sets the quality of embedded JPEG
- Mirror Lock up
- Selects the autofocus mode: AIfocusAF, ONEShot
- ISO 3200
according to the website.
Cheers
Dennis