MySpace, the king of social-networking sites, will have to face a new competitor: Facebook. During its F8 conference, Facebbok announced a major change, Facebook Platform, a new development platform that enables companies and engineers to integrate with the Facebook website and gain access to millions of users.

For example, Facebook jointly developed with Amazon.com an application called “Book Reviews”. The application will permit Facebook users to write and display book reviews on their profile pages. Facebook users can then click on the “Buy at Amazon” button to go to Amazon.com and complete their purchase.

“Amazon.com is pleased to be working with Facebook to develop exciting new applications using the Amazon E-Commerce Service from Amazon Web Services,” said Russ Grandinetti, vice president, Amazon.com. “With the Book Reviews application that will be released this week, Facebook users will be able to review, share and discover books they love with their friends, making their experience using Facebook more interesting and interactive. We're looking forward to working with Facebook to build many new and exciting applications for their users.”

But Amazon isn’t the only company that is ready to take advantage of Facebook’s new features. Microsoft’s Popfly is a web-based tool that gives Facebook users the power to create applications and add them to their profiles with no programming at all. For instance, users can create and embed mashups of websites directly in their profiles.

“The partnership between Microsoft and Facebook opens up exciting new opportunities that allow anyone to build dynamic, interactive applications using the Facebook social graph,” said Dan’l Lewin, corporate vice president, Strategic and Emerging Business Development, Microsoft Corp. “Microsoft has long been committed to empowering developers of all levels. Popfly and Visual Studio Express enable a broad new audience to experience the power of development.”

Facebook's ready acceptance of widgets is in contrast to MySpace, which has been more reluctant about adding the add-ons. Facebook CEO Mark Zuckerberg called the overhaul a "social operating system."

Facebook, originally targeted for college students but since expanded to other age groups, now has 24 million users and is growing at a faster clip than MySpace.