UPDATE 2-Salesforce offers Chatter to companies

* Lets companies build internal social networks

* Aiming at competing products from IBM, Microsoft

* Can pull information from Facebook, Twitter

(Adds comments from CEO, details on product)

SAN FRANCISCO/BOSTON, Nov 18 (Reuters) - Salesforce.com Inc (CRM.N) introduced am internal collaboration tool for businesses that it dubbed a Facebook for the enterprise, as the software maker continues to expand its range of cloud-based offerings.

The product, called Chatter, was unveiled on Wednesday at the company's developer conference in San Francisco. Salesforce said it's aiming at competing software products such as Microsoft Corp's (MSFT.O) SharePoint and IBM's (IBM.N) Lotus Notes.

Chatter will be free for current Salesforce customers, starting early next year. The company will charge $50 per user a month to those who want to use Chatter as a standalone product.

Chatter includes tools that will be familiar to most users of social media Web sites, including user profiles, status updates, content feeds and networking groups. It can also pull in feeds from Twitter and Facebook. The company said it took care to make the interface simple and intuitive.

Salesforce Chief Executive Marc Benioff said the company is seeking to translate its expertise in customer relationship management to collaboration management.

"In the past, the file sharing metaphor has dominated collaboration, but now this is a new opportunity to take the Facebook metaphor and use it for enterprise collaboration," he told Reuters in an interview.

IBM, Microsoft, privately held Ning and a handful of other companies already offer products that let employees share information about themselves with each other through closed corporate Web sites. Yet such tools have yet to gain the traction with businesses that Facebook has with consumers.

Salesforce helped pioneer software as a service, or SaaS. It sells subscriptions to use its business software.

Shares of San Francisco-based Salesforce fell 3.1 percent to close at $63.61 on the New York Stock Exchange.

(Reporting by Gabriel Madway in San Francisco and Jim Finkle in Boston; Editing by Matthew Lewis, Phil Berlowitz)