In GNOME 3.0 the notification area is deprecated. Therefor libnotify 0.7.0 comes with a lot of changes:
notify_notification_new_with_status_icon is gone
notify_notification_attach_to_status_icon is gone
notify_notification_attach_to_widget is gone
notify_notification_set_geometry_hints is gone
notify_notification_new has lost its widget argument
For more info you take a look at http://live.gnome.org/GnomeShell/Design/Guidelines/MessageTray/Compatibility
The attached patch made osmo 0.2.10 build with libnotify 0.7.0 again. Beware, it is dirty and does not check for the libnotify version.
Patch to make osmo 0.2.10 build with libnotify 0.7.0
Thanks for the patch. Should be fixed in R-904.