While a human study on the beneficial effects of calorie restriction is underway, researchers are still working with primate subjects in order to better understanding the processes involved. The University of Maryland Diamondback takes a look at a decade-long study of calorie restriction in rhesus monkies: "So far, the rhesus monkeys' calorie-restriction diet has produced results similar to those of the rodent study." In other words, better health and a slowdown in the measurable degeneration associated with aging. The human studies to date are producing equally good results, although the comparatively long human life span (still too short for my liking!) makes it much harder to find definitive data.
Link: http://www.inform.umd.edu/News/Diamondback/archives/2004/09/16/news7.html