Intel's latest roadmaps show a low-voltage quad-core Clovertown with a thermal design power (TDP) of only 50W:
There is Low voltage quad-core Clovertown to be released as well. Yet it’s coming in Q1 2007. So far, there is only one known LV model, Xeon L5310. Sharing the similar specification to E5310, it’s clocked at 1.6GHz with 4MB x 2 L2 cache and 1066MHz FSB.