Not only was his business built on top of the Twitter API, but his "key feature" was merely semantics. I'm not even convinced he should get the credit for originality, Stowe Boyd published an article on the topic in July of 2009 [1].

Companies that rely wholly on a third-party API aren't sustainable businesses, they're hobbies and oddly they have become overfunded hobbies. Twitter's starting to put a lot of hobby-companies out of business.

[1] http://web.archive.org/web/20091015145325/http://www.microsy...