Wikipedia already has a huge amount of up-to-date content, and so I wasn’t sure what the difference would be. After all, they both use MediaWiki as the server software, so wouldn’t it just be a duplication of effort?
Of course, Wikipedia covers topics as an encyclopedia would. Wikibooks will have books on the various topics. While the former would have an entry giving a broad overview of a topic, the latter might have entire books that go deep into the subject matter. For example, Wikipedia’s entry for the Ada Programming Language talks about the history of the language and its main features. It provides plenty of links to tutorials and other sites of interest, but the entry doesn’t provide any useful information to the student programmer. Wikibook’s entry for Ada Programming, however, teaches you how to program using Ada. It even has a link to the Wikipedia article!
People are getting excited about Wikibooks. For one, expensive textbooks that are outdated by the time they reach the classroom might be a thing of the past. Publishers might need to adapt, although I personally think that nothing can really replace solid hardcopy that you can read away from the computer. Another possibility is that classroom research might involve working with Wikibooks. Assignments might look like, “Go to the Wikibook entry on Set Theory and add any missing information to the Axioms section.”
It’s also scary. For example, Joe Schmoe might think he is an authority on usability and edit the appropriate page. If he has it all wrong, how will you know when you go to learn about it?
Of course, that same possibility exists for Wikipedia or the Game Programming Wiki, and those seem to work out pretty well. At the moment there are over 11,000 books in the database, and more will likely be on the way. They will likely get updated in a timely manner and will be superior to regular textbooks in terms of accuracy. Typos and errors will be fixed IN the book instead of on the publisher’s website under an Errata section. Perhaps most importantly, it is also freely and easily available knowledge! I’m sure Wikibooks will make a lovely addition to collective knowledge of the world wide web.