The Twitter API has fostered an incredible ecosystem: you only need to take a look at the sheer number of Twitter mashups that have been created to see that it is a popular Platform for developers. And while their public, rate limited API has at times limited the kind of applications that can be built, the Twitter platform team is looking to change this.
The Twitter Streaming API has been successfully used by Yahoo!, Google, and Microsoft, who have been given access to the 50 million daily public tweets, allowing them to integrate with Twitter on a much larger scale. And yesterday Twitter announced that it has now enabled this "firehose" of data for a number of other companies:
We are thrilled to announce that Ellerdale, Collecta, Kosmix, Scoopler, twazzup, CrowdEye, and Chainn Search join us as partners. These companies range from funded startups to part-time, one-person operations so we came up with a fair way to license access that scales with their business.