As I mentioned in one of my previous posts, BI vendors do not pay much attention to collaboration around BI deployments. However, this doesn't mean that large BI deployments don't have difficulties (or at least inconveniences) with collaboration and knowledge exchange. Some of these problems can be resolved using wikis:
First, and the most often problem -- lack of documentation convenient for both business users and technical team. Traditionally, project documentation (like specifications, glossaries, scopes of works, etc.) is done using Word/Excel documents. This results in network folders filled with tens or even hundreds of documents without any browsing possible. No need to say, that average business user will never look there. As BI-platforms doesn't have any good collaboration capabilities (excluding may be IBM), so user doesn't have many choices if he/she needs to know the logic behind certain indicator in a report -- only to ask somebody from tech team. In case of 5 users and 10 reports -- this is not a problem. But if you have 2'000 users and 10'000 reports -- this would be a problem. Often users, having such obstacles, just don't want to dig into details. And then we have low user adoption. So, reason #1 -- you need wiki to have the documentation searchable, manageable, consistent and convenient for use by business users first of all.
Reason #2 is that users usually don't have good How-To manuals. BI vendors usually do rather good manuals for developers, but in majority of cases they do not produce good illustrated manuals for business users. How to drill data, how to join data from two data sources, how to make ad hoc queries with subqueries, etc. etc. -- for all of these how-tos users need simple easy-to-understand illustrated manuals. And, what is important -- these manuals have to be easily extensible to target specific problems, if they occur.
And, finally, reason #3 is that large BI deployments typically have several BI tools. All of them have more or less decent portals for their own content, but none of them can hold BI content from other BI platform. Cognos knows nothing about BusinessObjects reports or QlikView application, Oracle BIEE knows nothing about Tableau and so on. At the same time a user might need access to several BI suites to perform his/her daily tasks. This is why you may want to have single subject-oriented (not tool-oriented) portal that would have links to various BI-content, or even have BI content embedded just in wiki pages. The latter may require some web-development works, as not all BI tools allow easy content embedding, and setting up integrated security, but it can also lead to much better convenience and user adoption.
There are a lot of wiki engines available -- free and commercial, easy and complex, etc. Wikimatrix can make the task of choice a bit simpler. I found DokuWiki to be perfect tool for majority of cases.