It still has a huge purpose. The wikibook stands to give /everyone/ with a browser a source of third party docs that don't fall under your jurisdiction and that can be changed or updated without "special access" or doc patch known-how. I'll admit though that when I created them the doc situation in Moose was /much/ worse than it is today.
I would still assert that it has strong assets, and that I still update it every now and then. I really like the