Yeah i've been wondering the same thing too.
There is a kind of paint called Fusion or something that works really well on plastics. If you clean thouroughly, sand with fine grit sandpaper, then clean again the paint should stick. If anything, read what it says on the can. The only thing is I wonder if any paint will actually hold up over time on surfaces that you touch every day. I painted the plastic panel around he shifter/radio and it turned out good, but I've never tried it on anything else. Also I was kind of uneasy about painting my perfect dash.
Link about paint:
http://www.krylon.com/main/pro...tails
So yeah, has anyone painted their interior trim pieces? Did it hold up? What did you use?