I work at Apple, on Safari RSS, a new feature in Apple's Safari web browser that supports discovering, viewing, subscribing to, aggregating and searching news feeds. Despite the name, it supports Atom as well as RSS (and prefers to parse Atom feeds given a choice.)
Thus far my co-workers and I have simply been implementing the Atom Syndication Format as described in the latest draft. Now that we're public, we'd like to start getting involved in the Atom standardization process too.
Home page: http://mooseyard.com/Jens/
Email: jens at apple dot com