Salesforce.com has launched a cloud computing business that enables developers to build applications on the software-as-a-service vendor's platform and tie those applications to Web services offered by Amazon.com, Facebook, Google, and other sites.

Salesforce first discussed its "Service Cloud" offering at its Dreamforce conference in November. During a San Francisco event Thursday, the company released pricing for the service.

The starting price is $995 a month, which includes the ability to create an online community for up to 250 customers, set up a contact center with up to five customer-service reps, connect to up to five partners, and tap the services of other sites.

Salesforce is providing the development tools for building Web applications that run on its Force.com platform and link to services on other sites. Salesforce's partnership with Amazon enables customers to connect to the online retailer's Elastic Compute Cloud service and Simple Storage Service. In addition, Salesforce offers customers access to Google's App Engine, which provides access to the search engine's spreadsheet, presentation, word processing, Web mail, and other applications.

Salesforce also offers tools for tying in to Facebook's social network, making it possible to connect to employees, customers, and partners in new ways. For example, at the San Francisco event, Salesforce showed how Orange, France Telecom's multinational wireless service business, is using Facebook to reach customers.

Orange has built an online community in Facebook that customers can use as a forum to discuss products and services. Orange monitors the discussions and uses the information to improve customer service and track problems with products.

With Amazon, Salesforce customers can leverage the retailer's data centers to get an extra blast of processing power through EC2 or more storage capacity through S3. The latest integration with Google expands on the companies' technology partnership, which started in 2006 with the integration of the search engine's keyword analytics service and Salesforce's CRM applications.

To Salesforce, which surpassed $1 billion in revenue last year, the Service Cloud represents a major step from the company's software-as-a-service roots to an era where service providers open up their platforms, so customers can pick and choose the services they want to use in their own Web applications.

"We really see this as our next billion-dollar opportunity," said Marc Benioff, chairman and chief executive of Salesforce.