so here is the deal with the newer boards. there have been several new board revisions in the history of xbox360, each one used a different chipset that uses less power which in turn produces less heat. Heat is the culprit for RROD so you can see how this would help the RROD situation. However kicks is still correct in that at this point even the jaspers have had some confirmed RRODs. The reason being that heat is not the only factor, other factors in the equation like lead free solder, and the thin motherboards that warp when they heat up. Even thought the jasper boards produce less heat, they still produce a crapton of heat, just less then previous revisions.
BTW if you want a jasper, look for the arcades with the 256MB memory card bundled inside, rumor has it those are all jaspers.