there is also this stuff called "Goo Gone" and it works really well. when i used to work at the mall, we would have visits where the owner of the company would come by and look at out store. we had all these ridiculous things to do like scrape off gum from our ceramic/concrete style floor. the gum came off so easily, i always volunteered to be the "gum scraper"...
i know that WD-40 is good at removing adhesive and i don't think it will harm the paint. you could also try using rubbing alcohol. i use that to remove the adhesive residue when i remove my registration sticker from my windshield. i'm not about the safety of it on your paint though...
-M-