I don't know of a single major enterprise that isn't experimenting with social computing behind the firewall. Every one of those organizations is also surely trying to figure out the best way to obtain business value at a time when "Enterprise 2.0 best practices" seem very circumstantial.
I'll propose a simple way to look at the challenge: The things you need to do for successful social computing within the enterprise are the exact same things you need to do to build an effective intranet (and vice versa).
This epiphany came to me when I was consulting for a global enterprise that had failed to create a credible intranet and was attempting to "leapfrog" several stages of intranet maturity by rolling out various Enterprise 2.0 applications instead. I call this "end-around 2.0." The strategy is alluring but ultimately limited. You launch a motley collection of social applications and try to get people to use them, but then what?
I find the "end-around" option particularly attractive to companies where a portal software initiative has calcified the intranet. (For more on how this can become a real trap in SharePoint, check with my EContent colleague Martin White at www.intranetfocus.com.) In those cases, "social areas" tend to get built outside the portal, almost as the "cool" part of the intranet. Yet, when you talk to the managers of those intranets, none of them ever wanted it that way. They recognize that employees need a flexible admixture of corporate and nonofficial information, official and informal communications. However, the company's Gibraltar of a portal application wouldn't easily accommodate that. So the company went around it.
The real key to effective social computing is the same key to making your intranet truly useful: user-centered design and development (UCD), which typically centers on personas and task analysis. You can find a rich literature on how to adopt UCD principles, particularly in an intranet environment. (James Robertson's www.steptwo.com.au is a good place to start.) Successful intranet managers already know this. According to a global survey by Jane McConnell of www.netjmc.com, UCD was the skill most designated "extremely important" by intranet managers (45% of them put it first).
UCD is how you get "into the flow" of peoples' work, and, to that extent, how you make social computing more relevant for their daily activity. You come to understand potential business value by converting requirements into common scenarios. As just one example: The needs of a project work team (e.g., "the Penske Account") can differ substantially from those of a global community of practice (e.g., "Sales Improvement") or country group (e.g., "Canada Team").
It's possible that the same toolset could support all three of those business functions, but a solid technology strategy would begin by identifying specific user needs in those contexts. In fact, when you start applying UCD rigorously, the conversation becomes much less about any individual application to a broader focus on integrated packages, community-specific team spaces, and user support.
"Surely," you might be wondering, "there must be models for this out there." As a matter of fact, you can find a variety of intranet maturity models. I personally like Robertson's, but you should just pick one and apply it. All the models tell intranet managers to fight for a dedicated team, to work to improve search and content management, and then to add useful business services. They don't prescribe "getting social" as if that's just another step. It should be part of what you do all along.
So, for example, you still need a well-functioning CMS, but you also need social services on top. If your colleagues can comment on a blog, why not on an article or any other piece of information? Adding pervasive commenting helps ensure that your discussions don't become as siloed as your information.
In the end, I understand the frustration with sclerotic intranets that leads to cop-out-by-wiki. At a time when many enterprises are trying to improve their intranets with more active corporate communications (borrrrrrring!), we can all see the value of more effective employee communications.
Yet, people who say, "We don't need a better intranet; we've got wikis" are missing the point. To get value from social computing at an enterprise level, you need some specific roles on your intranet team. Here are some that I've seen: "User Experience Analyst," "Community Organizer," "Metator," "Teacher," "Seeder," "Reverse-Mentor." And so on.
Unlocking business value requires finding those skills. All the social goodness can follow.