The common shorthand description of enterprise social networking is "Facebook inside your company"--not literally Facebook (although it's possible public social networks will enter this market) but software that mimics some of the functions of a public social network, while adding features specific to use within a business. The early adopters are looking to add some of the spontaneous social interaction associated with consumer social networks, but with the goal of business productivity rather than pure entertainment.
Consumer social networks are media properties programmed to observe the interactions between individuals for clues on how to deepen their engagement with the service (for example, by connecting them with people and content that match their interests) and, ultimately, make them a rich target for advertisers. Enterprise social networks can use the same techniques to divine a user's professional interests and expertise, suggesting colleagues and discussion groups they might be interested in connecting with. In the enterprise, the focus is on making people work better together. Enterprise social networking software takes on some of the same functions as portal software in allowing personalized views of information, but social software elevates the role of people, making it easier to navigate from a document to the profile of its author and from the profile to other documents--or groups, events, applications, and activities--that person is associated with.
Enterprise social networks must also meet an organization's security requirements and integrate with other content, collaboration, and identity systems.
Jive Software just had a successful IPO on the basis of its social software, and what they are showing in this screen shot is how your home page on the corporate network can bring together all sorts of information about what your coworkers are working on and information they have chosen to share. This is a social network organized around work, so you can see what's going on with projects or teams you're associated with. Also, just like Facebook recommends people you might want to have a friend connection to, Jive recommends interesting people and topics you might want to follow.
With the Apps Market introduced in Jive 5, Jive is also trying to turn itself into an integration platform for lots of other social applications, in much the same way Facebook has created an ecosystem of partnerships with the creators of social games and applications.
Jive is one of the best known players in internal enterprise social networking and also makes software for managing external communities (such as discussion forums for customers). The IT advisory firm Gartner ranks Jive as a leader in both categories, whereas many competing products are focused on one or the other (Jive says its revenue is split about 50-50 between internal and external applications).
This is a young market, with many competitors and new ones emerging on a regular basis. This slideshow provides an overview of some of the major players, but it is not a complete list. It also shows examples of how social software is being applied by specific organizations.