Evolution should be split into separate Mail, Contacts, Calendar/Tasks, and Memos applications in the Ubuntu Applications Menu. Each application should open in a separate menu.
This would make Evolution less intimidating for people who only need email and object to leaving a full-on Outlook clone running all the time. Evolution is very well integrated in GNOME, but these people still switch to Thunderbird because Evo feels so 'huge'. They're missing out on the integration, and they're *still* running evolution-data-server in the background!
If you look at the source, it's evident that Evolution is already made up of separate programs - Mail, Calendar, Tasks, Contacts, etc. - all held together by a 'shell' program which combines them into a single window.
Also, most of the work of connecting to mail servers and storing data is already performed by evolution-data-server and friends, which are completely separate from the Evolution UI.
This change has been discussed on the gnome-desktop list before.
It should also be possible to switch back and forth between the Combined Evolution UI and the Separated UI mode being proposed here.