[<< wikibooks] Models and Theories in Human-Computer Interaction/Activity Theory and Platforms Like Wikibook
Wikibooks as a collaborative medium for a group that can't meet in person is not a bad choice. Other online tools such as GoogleDocs, GitHub, and some cloud based file storage systems exist and offer online meeting and collaborative systems and many of them are widely used because they do improve a groups ability to work together when face-to-face isn't an option.
There are drawbacks though, such as a phenomena dubbed social loafing. In an environment such as Wikibooks, there is an element of anonymity and it becomes easy to lose accountability, and since there are other people who could get the job done, some people will try to shrug responsibility. It is similar to a phenomena that occurs in non-virtual settings called diffusion of responsibility, it is a phenomena that occurs when a situation calls for someone to step up, and there is a crowd of people. One would think that with all those people, at least one of them will try to help, but instead, everyone stands there expecting someone else to do it.
Social loafing and other problems with accountability and responsibility in online collaborative environments can be reduced or eliminated by taking the right measures, like dividing the work and giving everyone something to do, don't just divide it and leave it for everyone to tackle a part, assign those parts to individual people. This would seemingly require someone to step up and take control, but it could just as easily be managed by 2 or more active people, that way no one gets labeled a tyrant or anything.