Having a search functionality on your Intranet is a good start. However, if you really want to tap into the knowledge available within your organization, you shouldn't settle for just surfacing the most popular content in the search results. Extra effort and investment in developing and maintaining your enterprise search capabilities is needed in order to get to what Alex Dowbor calls "buried information" in his slide describing the Long Tail of Enterprise Search:

Read the article and blog at http://ornot.ca/2011/03/07/the-long-tail-of-search