It's got an odd name, but Wikipedia has become the new encyclopedia. Oddly enough when you search google, you are more likely to bring up the Wikipedia article than an encyclopedia article of any kind. The Harvard Business School had an interesting post on why and how Wikipedia works.
It is definitely ironic how we move forward assuming that the information on Wikipedia is true. In most cases, Wikipedia works, but obviously shown by this article, there are errors in the published posts, however not many more than you'd find in an encyclopedia. Does this make one facet of information more truthful than the next? I know for a fact that I've looked up information on Wikipedia, but I never check another website for the validity.
On the other hand, Wikis have expanded past just informational encyclopedic sources. In another blog on Slate, this post demonstrates some of the shortcomings of Wikis. There again WikiTravel is very new and perhaps in 10 years, it'll be better than your average Lonely Planet.