UPDATE: Bug resolved with patch that adds a gconf preference defaulting to false. There is no UI to toggle this preference. The relevant key is /apps/tomboy/enable_icon_paste.
As posted to tomboy-list...
With regards to bug #359167, does anybody actually use this feature?
Most GNOME applets let you move them by middle-click-dragging. With Tomboy, when you middle-click on the applet (or notification icon), any text in the clipboard is pasted to the Start Here note, which is opened for you. I don't think this is documented anywhere.
Would you care if this feature went away?
Personally, I never use the Start Here note, so I'm probably not qualified to judge whether or not it is a useful feature.