I believe this broke because nm 0.7.0 doesn't emit all the same signals as 0.6.5
With Evolution open, I tried disabling and re-enabling networking with NetworkManager and Evolution seemed to follow along. It updated its online / offline icon (lower left corner) each time I changed something. Maybe the API didn't break after all? NetworkManager-0.7.0.3-svn2970.fc8 evolution-2.12.0-8.fc8
I believe Evolution uses NetworkManager-glib, in case that provides any clues.
Demoed this working to Matthias and we agreed to close the bug. The NetworkManager-glib API hasn't changed, so we're good for NM 0.7.0.