This is a big deal for Drupal — it's not every day that one of the hottest technology start-ups switches one of its sites to Drupal. At Acquia, we have been working with Twitter on this site but couldn't talk about it for the longest time. I'm glad we finally can because it's a great use case for Drupal.
Twitter has 750,000 developers who have created nearly a million apps, making 13 billion API calls per day. Those are some astonishing figures! A population that big requires a lot, as we in the Drupal community know.
Fortunately, Drupal handles big communities well. Developer communities have been quick to recognize that and have adopted Drupal at a remarkable rate. Among them are the Brightcove developer community, Symantec Connect's developer community, DivX's developer community, and many more. Drupal's own website, Drupal.org, has more than a million registered users and is one of the largest developer communities in the world. Needless to say, drupal.org runs on Drupal.
Twitter is a curious case. On its face Twitter only has to do one thing — deliver short messages in one-to-many mode. But its published APIs (and enormous popularity) have led developers to create a lot of interesting things. That's also why Drupal sites can publish to Twitter, and vice versa, via the Twitter module.
In the end, that is what good developer communities are all about. Developers are like molecules, vibrating with intensity and vigor. Their individual movements can seem random. But together in the right environment, they can form waves — or snowflakes. Nurturing a community in which both are possible is the challenge every software project faces; I'd like to think that Twitter, through Drupal, is creating the right environment.