I find Flickr a really interesting site as it contains a great sense of community, through it's use of groups especially. There are endless groups on there, covering any and every subject you may want to consider for photos - or videos, confusingly - with nothing to prevent anyone from setting up their own group. All very 'Web 2.0' with social networking to the fore. Flickr also benefits from promoting work for shared use according to the 'Creative Commons' licensing scheme.
As well as the use of groups to post and share pictures with a common theme, the site allows you to register your contacts so that you can see what they are posting. This helps to build an extended network of contacts that may even become friends, not just virtual stalkers (although I am sure an element of that exists, for which you can block people from marking you as a contact). With this network approach, plus groups, there is a strong sense of community as people comment on each others work, whether providing criticism (requested or not) or just well-wishing or paying compliments.
I feel that maybe this collaborative approach to sharing information, viewpoints and feedback could do well if it could be mirrored in a business environment. Characteristics would include minimal control being exercised by moderators (or 'management'), notification of new content, subject-based group areas, networks of contacts. exchange of views and 'feelgood factor' that can arise from shared aims and contributions. Now, I've seen many Wiki sites and SharePoint portals that are supposed to provide all of these points - from a technical perspective, anyway.
So if the internal business sites do not get used in the same way, maybe that points to the company culture not being conducive to open comment and shared efforts to reach goals? Is there really a no-blame culture; are people scared to speak up and possibly be proven wrong; does the company want people to work in a more team-friendly way; or is there a lack of trust to be resolved? Plenty of possible reasons why this can happen, and [most of the time] I would think it is not a deliberate company policy, but just an environmental issue.
If you are in an influencing position (which should apply to *anyone* in an organisation), then maybe look at what technical facilities are provided for use in your company, but that which are perhaps not being used in anywhere near their optimum way. If you agree that things could be much better, why not look at the culture and environment to see if you can contribute to improving things, or be sure that staff are empowered to move things forward in such a way.
Or if there is no real intention to make wider use of those portals, discussion boards, Wiki pages and the like, perhaps you should just save the time, effort and money and rip them out. If they aren't being used (by readers or writers of content), make a bold decision and drop them! Better still, take the other, easier, decision and promote these facilities; get them more widely used, make them easier to access and and more frequently updated. Get the value from this investment, whilst perhaps improving the way in which people get to do their work...