This is an area I am interested in also. I run two groups of Mexican students who work with Wiki project for their "servicio social," a community service requirement for all Mexican undergrads. There was some question this semester as to whether the program should continue as they were looking for evidence of "social impact"... which they were defining as students having direct contact with beneficiares (think reading to children or serving food at a soup kitchen). We did convince the powers-that-be that while there may not be face-to-face, we can provide numbers as to how many people access the materials that students create/improve (but cannot break it down as to how many of those are from Mexico).