∞ Siri co-founder leaves Apple

Kara Swisher:

There were several reasons for the departure, which was amicable and has been planned for a while, sources said. They included Kittlaus’s family being in Chicago, a desire to take time off and an interest in brainstorming new entrepreneurial ideas.

From what I heard, Apple moved Siri along quite a bit since acquiring the company, so I think they have a good handle on the technology.