Why Atom? Cell Phone Blogging.
Sam Ruby blogged about an application under development at Nokia called PhotoBlog, which implements the Atom API and enables one to post to a blog via a cell phone. That would be really cool and would probably inspire me to get whatever reasonably-priced phone supported it, once MT implements the API. (Hopefully, version 3.0.)
Update: Oops. Nokia isn't developing PhotoBlog; Futurice is. Nokia's CTO introduced the application at a trade show.