brakes for carbon rims
Most carbon rim manufacturers like zipp and enve recommend a brake pad of their own.  However, there are typically several pads that will work.  Most of these pads are designed specifically to work well on carbon rims. Regular brake pads from alloy rims should not be used on carbon.

Zipp recommends the following pads for their rims:
Zipp Tangente Platinum Pro
Zipp Tangente cork pads
Bontrager cork pads
Zipp carbon/carbon pads
SwissStop yellow pads

So, I would check with the manufacturer of your rims to see what pads they recommend and stick with those, otherwise you could be voiding your warranty on an expensive set of rims.

Leonard Zinn (author of Zinn and the Art of Road Bike Maintinance and owner of Zinn Cycles) recommends against using regular pads on carbon rims.  See the following from the article in velonews:


  I can say from personal experience that standard brake pads on
  carbon rims are grabbier, giving louder, less predictable, potentially
  dangerous braking, and they wear faster, even melting down rapidly at a
  critical moment on a long, fast, tortuous descent, leaving you with no
  brakes at all. Furthermore, conventional pads on carbon rims are
  down right scary in the rain, making for unpredictable braking until the
  rim is wiped clear of water enough for them to grab.