Facebook Platform to go open source — but how open?

Updated with confirmation

Facebook is about to make its third-party developer platform open source, according to TechCrunch’s Michael Arrington. That could be a huge step toward breaking down the wall between Facebook and the rest of the web.

What this means, basically, is that applications developed on Facebook Platform would be compatible with any social network that maps its application programming interfaces (APIs) to Facebook.

Facebook has been sending out mixed signals on how open it wants to be — it caused a bit of an Internet brouhaha after cutting off Google’s Friend Connect, but it also just announced a feature called Facebook Connect, which lets users access their Facebook identity on any site. I’m hardly the first to say that it’s a smart and necessary move for Facebook to make itself more open, particularly as Google’s OpenSocial initiative picks up steam and startups like Ringside Networks are getting buzz by making Facebook apps compatible with other websites.

Arrington is less clear on exactly how open the open source version of Facebook Platform will be — specifically, to what extent social networks and other sites will be allowed to customize the platform for their own use. For those details, we may have to wait for the official announcement.

I emailed Facebook to ask if they can confirm and offer more details, but I haven’t heard back yet.

Meanwhile, Reuters looks at the “cottage industry of speculation” about the possibility of Facebook’s IPO. Not surprisingly, there are still no convincing signs that an IPO is coming anytime soon. (We boiled down the rumors that Microsoft wants to buy Facebook last week, and Kara Swisher chimed in today to argue that it makes sense for Facebook to sell.)

Update: Facebook just sent me a statement confirming the rumor:

We’re working on an open-source initiative that is meant to help application developers better understand Facebook Platform and more easily build applications, whether it’s by running their own test servers, building tools, or optimizing their applications. As Facebook Platform continues to mature, open-sourcing the infrastructure behind it is a natural step so developers can build richer social applications and share what they’ve learned with the ecosystem. Additional details will be released soon.