Whereas many such projects seek to encourage input from everyone, others are adding in a layer of filter and publication. For example, the Stanford Encyclopedia of Philosophy has a Wikipedia-type approach, but with an additional layer of editing, so that ‘all entries and substantive updates are refereed by the members of a distinguished Editorial Board before they are made public’ (http://plato.stanford.edu/about.html). In this way they hope to combine the power of user-generated content with the reliability of a scholarly reference work.
The demonstrable advantage of such open approaches to data gathering for specific projects is leading to this being an increasingly popular methodology. The problem for such projects is in gaining sufficient contributions, and knowing how to promote this and generate appropriate levels of interest will become a relevant research skill.