I'm not an expert here, but it's pointless to make tracking sun panels that costs a lot more if the outcome wasn't that great, I bet tracking sunlight is still more efficient even after spending energy to move the panels, it makes no sense otherwise. The real benefit of this is that you get a cheap motionless panel that performs a lot better than the flat version, this is specially important in places like Africa where you need to be as efficient and cost effective as possible.
SolarFlower.org - the open source solar collector - has a non-electronic sun tracking system that I think might be more efficient than PV-powered tracking. See http://www.solarflower.org/faq.htm.