Facebook has decided to share some details about its system architecture and make public the source code that powers it. In a note posted by one of the company’s engineers, Facebook describes how it went about choosing its technology stack and ultimately arrived at the decision to build its own server – called Scribe – to make sure Facebook could scale to hundreds of millions of users.

Scribe is available as a project on SourceForge, where developers can track updates, request features, and submit bug reports. Facebook has a number of other open source projects in the works, including Facebook Open Platform, which offers up much of the Facebook code and enables other social networks – like Friendster – to let developers easily migrate their Facebook applications over.

Unlike other social networks like Friendster, MySpace, and Twitter – all of whom have run into serious scalability issues at different points during their growth - Facebook has been mostly reliable throughout its rise. So, if you have the bravado to think your Web app may someday handle “a few billion messages a day” (as Facebook says in their note), you may want to give Scribe a look.