There is a world of difference between having a tool and knowing how to use it, and between knowing how to use it and making it an extension of oneself -- knowing how that tool sees the world, being able to reinterpret any situation in that context. The expression "when all you have is a hammer, everything looks like a nail" has both positive and negative aspects. There is utility in being able to see the nail-like aspect of any problem, whether or not there is a hammer handy (in particular, one should regularly be considering how important it is to find a hammer, if one is not).
When it comes to wikis - there is much more to effectively implementing an open collaborative content aggregator than having and using one. Content workflows with detailed roles (protection, privacy segmentation, &c), continuing use of other information channels for public sharable knowledge (email, blogs, whiteboards, phone calls, ticket systems) that don't pass through the wiki -- all of these limit the scalability and efficacy of a wiki's openness.
For the purposes of OLPC : if we want the public to take an active part in guiding and advising on the project progress, news and photos and updates should come through the wiki first or second, not as an afterthought when someone remembers. Wiki watchlists should be a key part of tracking new ideas. Educators, officials, students, other community members should all be directed to the wiki for sharing their thoughts and discovering what is going on -- withthe caveat that if they can't find what they're looking for, they should ping someone to update the information here. And internally, using a wiki to organize text and project ideas will help accustom project members to that style of formatting and interlinking thoughts.
Please leave me comments and tell me what you think.