The article about the Ethiopian kids reminded me of an old Tech talk that I had seen (Link - http://www.ted.com/talks/sugata_mitra_shows_how_kids_teach_themselves.html)
A similar experiment was done in 1999 called as the "Hole in the Wall" project, where an internet-connected PC was embedded into a hole in the wall of an urban slum in Delhi. A touchpad was provided next to the screen for the controls. It was soon noticed that kids who did not know English including some school dropouts, approached and played around with the touch pad controls, sometimes making accidental clicks that opened up a browser and opened a whole new world of internet browsing. This experiment was repeated across several villages in India. The common observation was that the kids were curious, and self taught themselves the new language, and shared it with other new kids.
So yes, it is human nature to eventually learn about a tool even without an instruction manual. Be it using a laptop in the case of the Ethiopian kids or the case where man discovered fire while striking two pieces of stones. But the point is, could things have been faster if an instructor showed them how to use a laptop? Perhaps yes!
I say this also by experience from the refugee computer literacy classes for adults. In the first session, we usually have students with limited English vocabulary, and zero or minimum knowledge about the computer. But they have amazing grasping power, possibly because they "want" to learn and are passionate about it. They would also probably tell you that the initial info we give them about certain things is useful. Would they have eventually figured it out? Sure. But many of these students are hungry for knowledge because they want to survive in a new country....find a job, catch up with the rest of the population, and be able to help their kids with school assignments.
To conclude, though the OLPC experiment sounds like a good initiative, there obviously are many more things to think about before just handing out laptops to kids. We must not forget that laptops cannot replace teachers or even parents :)