Pretty much everything I've read (for example, this page) says not to use wood, because the oils from the peppers will penetrate the board and transfer, and hold there indefinitely, even after thorough washings.
This thread is full of people with personal experience transferring the heat to later meals.
That said, as with Jefromi, I've cut hot peppers on wood before and not noticed any transfer. Specifically, home grown habaneros and jalapenos on maple boards.
Maybe I'm just acclimated to the heat and don't notice, but those recommendations are not in line with my personal experience. I do thoroughly scrub my boards after use, but that probably isn't washing away any residual oils.
If you really want to be safe, for example if someone in your house is heat sensitive or you have small children helping in the kitchen, you can dedicate a board to cutting peppers, or just cut peppers on a small plastic board and wash thoroughly after each use.