Technical overview of Facebook's Haystack photo storage system - and why they removed their dependence on a traditional file system to deliver photos.

Quoted: This week Facebook will complete its roll-out of a new photo storage system designed to reduce the social network's reliance on expensive proprietary solutions from NetApp and Akamai. The new large blob storage system, named Haystack, is a custom-built file system solution for the over 850 million photos uploaded to the site each month. Jason Sobel, a former NetApp engineer, led Facebook's effort to design a more cost-effective and high-performance storage system for their unique needs.

A catalog of Facebook's open-source projects.

Quoted: Facebook is a social utility that connects people with friends and others who work, study and live around them. People use Facebook to keep up with friends, upload an unlimited number of photos, post links and videos, and learn more about the people they meet.

Not only is Tornado open-sourced - it looks like they have done a really nice job of documenting the framework as well on this dedicated site.

Quoted: Tornado is an open source version of the scalable, non-blocking web server and tools that power FriendFeed.

FriendFeed open sourced their web server technology, "Tornado" this week.

Quoted: Tornado looks a bit like web.py or Google's webapp, but with additional tools and optimizations to take advantage of the non-blocking web server and tools.

(thanks, Roy)

Quoted: New ways to use Facebook have already begun to emerge now that the site's creators opened key parts of its technology to outside software developers. Thousands more are likely, Facebook says.

Is the stream.publish API out of "beta" yet or not? Claim here is that only developers can grant permissions to this API now.

Quoted: At this time, while the Open Stream API is in beta, the only Facebook users that can grant your application the publish_stream permission are the developers of your application.
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This method is similar to feed.publishUserAction, but is much simpler because you don't need to create templates before publishing into a user's stream.

Latest API for access the user activity stream.

stream.get - read the user's stream
stream.publish - write to the user's stream and update status

Changes to news feed API's

Quoted: However, if you have any user-generated content in your feed stories such as a review or user comment, you should redo your feed templates and start passing that in as "user message" parameter rather than in the body of the feed stories.

Web sites can intergrate with Facebook via Facebook Connect.