Microsoft calls it TownSquare. Deloitte hosts D Street. IBM has its Beehive, and Best Buy its BlueShirt Nation.

No, it's not a real estate explosion. In industries from retail to high tech, banking and manufacturing, companies are increasingly building networks behind the firewall where employees can create profiles and connect with one another in ways first demonstrated by LinkedIn, Facebook and MySpace.

"The whole Web 2.0 explosion has moved from the consumer and college student world to professionals in the business world," says Amy Shuen, author of Web 2.0: A Strategy Guide. (O'Reilly Media, 2008). "Employees are seeing this as a way of enlarging their sphere and interacting with colleagues."

It's more than an electronic water cooler, she says. Companies may start with the idea of helping employees feel more connected, but that's just the beginning. With easier and faster connections among people, suddenly cross-division collaboration happens more naturally, leading to greater innovation. "People don't just chat; they connect with people and end up talking about things that have an impact on the business," Shuen says.

Forrester Research agrees that 2008 is a time of rapid adoption of internal social networking, citing software suites that include social networking features, such as Awareness Inc.'s Enterprise Social Media, Jive Software's Clearspace, IBM's Lotus Connections and Microsoft's SharePoint.

Here are three companies that are already seeing benefits from early adoption of internal social networking.

Deloitte: D Street

The idea for Deloitte's D Street began when the firm's talent organization wanted to make a large company feel smaller. In addition, it wanted to create an environment that would appeal to its mostly younger workforce. At a company where the average age of employees is 28, "we knew we had challenges to win the talent war," says Patricia Romeo, the leader of D Street. But in January 2007, when the group began to create the business case for the social networking environment, it also started to envision some of the side benefits the initiative might engender.

For instance, by enabling connections among employees, the company could more easily offer flexible work arrangements, establish virtual teams, bring new employees up to speed, improve collaboration and increase retention among people who hadn't felt a strong sense of belonging.

After getting the support of Deloitte leadership and partnering with internal IT, communications and knowledge management groups, the team launched the alpha version of D Street in June 2007, basing it on a commercially available collaborative platform. The initial rollout was to 1,500 employees.

Romeo describes D Street as having capabilities similar to Facebook's, except that profiles are prepopulated with basic information, including name, job title and contact information. Employees can personalize the profiles with things like photographs, resumes, work and community affiliations, and former employers. D Street enables workers to introduce colleagues to one another, list external social network memberships and write blogs. There's also a "guest book," in which visitors can leave comments.

And D Street helps people connect. An employee who searches on "Web 2.0," for example, will find other people interested in that topic, as well as their connection to him.