Facebook looks cozy with Microsoft, Amazon — a challenge to Google?

During Facebook CEO Mark Zuckerberg’s keynote today, senior representatives from Microsoft and Amazon came on stage to demonstrate how they’re integrating their services with Platform. Google was nowhere to be seen. Forget the Facebook-Myspace rivalry — could an anti-Google triumvirate be forming?

Zuckerberg told us he went to Redmond several days ago to talk with Ray Ozzie, Microsoft’s Chief Software Officer, because the company has experience building “big apps.” The two companies are openly close, with Microsoft (not Google) providing contextual banner advertising for Facebook at a premium rate.

Especially after rumors earlier this week about Google and Salesforce teaming up, a Facebook-Microsoft appears mutually beneficial. The 24 million-plus active users of Facebook getting plugged in to Microsoft’s vast array of offerings. In fact, during the keynote, Microsoft’s Silicon Valley representative, Dan’l Lewin, openly discussed using integration to better serve small-to medium-sized businesses — also Google Apps’ target. Initial efforts here have already been made, with Facebook profile photos being integrated with Vista applications.

Facebook and and Amazon have also worked together to develop an application called “book reviews.” (These applications are going live tonight, around midnight, so no URLs yet.) Facebook users can write and display book reviews on their profile pages, then follow a “buy at Amazon” button — and the two companies say that they have more applications in the works. Amazon also has existing ties with Facebook: Owen Van Natta, Facebook’s COO, came directly from the company.

Microsoft and Amazon are both are competing with Google on multiple fronts; Facebook, meanwhile, competes with Google’s Orkut. Facebook Platform gives each of these three companies a new way to stay relevant to users, especially younger demographics, even as Google continues to expand its own lines of products and integrate them together.

This may also be bad news for startups. On the good side, Facebook will let users pick and choose their own apps — and they can remove Facebook features like “notes” or “events.” So startups, including many of the 65 Platform partners at F8 today, do have equal access to Facebook users. If Facebook users prefer a startup’s app to those of Facebook, Microsoft or Amazon apps, that startup will succeed without interference. Except that Microsoft and Amazon can now tie in their millions of users to Facebook.

Of course we had to ask Zuckerberg the big question. Did this notable warming with Microsoft suggest a possible acquisition may be in the works? Zuckerberg said Facebook is not entertaining an offer.