Evolution features virtual folders, advanced filtering, spam filtering, security, calendar, todo list and contact management, Exchange support, signing mail with S/MIME / GPG / PGP, and syncing with palm pilots.
This should be very exciting for people who are stuck having to use Exchange / Outlook (through either choice or decree from The Bo$$tm) and are looking for an alternative to some of the less-than-perfectness that is MS Outlook.
A quick test here shows it's far from perfect. Default window layouts are odd (you have to turn on status bars, sidebars, and toolbars), and it took a bit of finagelling to just get to my exchange mail, which then wouldn't load. A bit disappointing, but there is definate promise there, and there's still a decent pop/imap client there. Anyone else played with Exchange with this new Evolution?