John Naughton retells the story of some great encyclopedias in The Observer. The rise of and fall of Britannica, then Encarta and the present debates over Wikipedia.
The debate is only partly about accuracy of content; it's also about suitability of format. For centuries, books were the only suitable format for a comprehensive encyclopedia. For a few short years (the Encarta age), CD-ROM publishing seemed to be the future. Now we know that it was replaced by the web.