Twitter is one big social network! With over 500 million users, 200 million that active monthly - it definitely has lots of eyeballs looking at it. For most of us that are into social networking and love tweeting most likely also viewed the official Twitter's blog from time to time. It is a great resource to learn the latest news and happenings from the world's second biggest social network.
You would think their blog would have been built on the popular WordPress platform, as it is used by millions of others and is extremely search engine friendly. They didn't. They also didn't go the Google Blogger Platform route like they had previously. The refreshed Twitter Blog was built in Drupal.
Drupal is a great open-source blog platform and has a lot of benefits that aren't available in WordPress and other CMS's. One very important reason is its security and protocols. For a top viewed website such as Twitter getting hacked can be extremely critical.