The XIM (Xbox Input Machine) was originally designed to enhance the functionality of the XFPS, which is a keyboard and mouse adapter for the Xbox 360. However, with the right ps2 adapter, you can make it work for the PS3. The use of the XIM by PS3 owners is growing in popularity. You can view my XIM's on ebay at the following link:
XIM mouse/keyboard adapter for PS3 and Xbox 360 (XFPS) - eBay (item 160284908278 end time Sep-26-08 11:46:07 PDT)
There is also a link on the auction page for the PS2 adapter you will need.
Don't hesitate to ask any questions. You can send me a message through ebay using the "ask the seller" option.