The Linux Foundation has a video up of a presentation given by Chris Aniszczyk, Open Source Manager at Twitter: http://video.linux.com/videos/open-source-at-twitter
Last year, [Twitter] established an Open Source Office (@TwitterOSS) dedicated to supporting open communities important to us and to maintain a healthy, reciprocal relationship. We’ll talk about some of the challenges in establishing an open source culture and also go over some of the open source technology behind a Tweet.
The experience of Twitter can be used as a guideline for your own organization’s experience with establishing a free/open source culture.
The key thing to remember when watching this video is that some of the same principles apply to organizations of any size. You don’t have to be a startup or have a startup culture like Twitter in order to establish this principles.