Facebook is open sourcing its application platform and calling it FBOpen. From Techcrunch:

Facebook will turn the year-old Facebook Platform into an open source project, multiple sources have told us. The immediate effect will be to allow any social network to become Facebook Platform compatible – meaning application developers can easily take their Facebook applications and have them run on those social networks, too.
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They’ll simply map their existing APIs to Facebook Platform (which isn’t trivial) and go. Expect to see the four major technical pieces of Facebook Platform – FMBL (markup language), FQL (query language), FJS (Javascript library) and the Facebook API to be open sourced and made available to anyone.
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This is a nearly inevitable response to Open Social, which is backed by Google, MySpace and Yahoo. Open Social is also an open source platform, run by the Open Social Foundation

Given that the FB platform is up and running with thousands of apps on it my guess is that many other social networks will start to think seriously about whether they are better to join the FBOpen bandwagon than get involved with what one of the commenters to the Techcrunch post described as the ‘Open Social mess’. Remember that Bebo already uses the Facebook platform.

If adopted by other social networks the FB platform will become more attractive to application developers – which is a (maybe the) key battleground between Myspace and Facebook these days.

Interestingly, as ReadWriteWeb points out whilst the war for social network supremacy is between Myspace and Facebook, the current battle over standards is between Google and Facebook.

Where I would disagree with ReadWriteWeb, though, is in their assertion that this standards battle between Open Social and Facebook is not beneficial to app developers and end users. Whilst I agree it would have been better if there had been a single well implemented standard from the beginning, given where we are today Facebook’s move to open source it’s platform will force Open Social to up its game and may even result in the community improving FBOpen. I think that will be good for everyone.

Where I am in agreement with ReadWriteWeb is in the belief that data portability is the bigger issue. I am hoping that as open-ness becomes the natural state of affairs we will see progress in this area too.