"Evolution 2.0 is the stable version of the 1.5.x development series. It
will upgrade your existing 1.4 install if you were not using 1.5
previously, but will not delete it until told to.

Major New User Features:
* NNTP support
* S/MIME support
* Integrated Junk Filtering with SpamAssassin
* Web calendars
* Overlayed calendars
* Improved UI
* Many bug fixes

Major New Developer Features:
* Simplified component creation, its much easier to write your own
component now
* The calendar and address book data is now available via the Evolution
Data Server (formerly the wombat) without requiring the Evolution client
* Generally improved internal architecture"

Gnome