InternetNews.com has a long story about a new enterprise wiki service called BizWiki from CustomerVision that includes some interesting discussion about enterprise wiki use in general.  Some highlights from the article:

It's all about capturing knowledge before oldsters retire - retaining intellectual capital and dynamically building a content bank.  Mass retirements may be right around the corner and organizations need to find effective ways to prevent devastating knowledge loss.

One Bank exec says he's using the wiki to respond to e-mail questions more efficiently.

"Financial services entities need quick, clear and concise responsiveness to electronic customer inquiries; these cannot take days to be responded to, nor can they build up into a project," he said in an e-mail to the author of the article.
The wiki company doesn't talk about wiki technology, they say, instead they focus on the need to collaborate.  The company site's front page does have the word wiki all over it, though - so it's not as if they are hiding anything.

The company says their software (and I'd contend wikis in general) are as easy to use as email and have much of the power of a formal document management system.

An interesting cautionary point:  the company emphasizes that enterprise-wide wikis are far less likely to be useful than wikis targeting particular communities of interest in an enterprise.  That's true of knowledge management initiatives generally, it's said.  It's in the Community of Interest/Practice context that key information is most likely to be findable and shared.