eMail that makes sense

It's a little close to Christmas to be geeking out too much, but with the sheer amount of email I receive daily, I found this article interesting.

Basically, it outlines a new way to look at threaded conversations, transforming what is often a confusing, linear stream of messages (1 dimensionally) into something that traces the conversation both chronologically and by sub-threads - or who replies to what (2 dimensionally - get the pretty picture?)
As vital as email has become to most people's work habits - with the noted exception of my mother (who still believes the internet is some form of 'voodoo') - there's really been very little in the way of true innovation in the way we read and keep track of email since the late 80's. Outlook is prettier than PINE, but not necessarily more functional

As a random poll, is anyone using something other than Outlook (or Express), Lotus Notes, or Eudora anymore? (Note: webmail - hotmail, yahoo, or anything accessed via the browser - doesn't count)