In the November issue of the Journal of Chemical Education May et al. of the University of Michigan report on their experiences with a classroom project aimed at improving Wikipedia (DOI). Students were given topics with instructions and started or expanded the corresponding Wikipedia articles. Examples are asymmetric induction (see before and after ) and fire-safe polymers. Overall their experiences were positive. Luckily the article did not complain about the grumpy old men (myself included) that patrol the chemistry pages and demand that newbies publish proper licences with their images or include DOI's with their references.
Notable observation: the students are more motivated and critical in writing for wikipedia because the result is publicly visible and for eternity.

Helpful links:
Wikipedia:School and university projects
Wikipedia talk:WikiProject Chemistry