I haven't either. I have interacted directly with specific connections in terms of offering my services (& vice versa), but haven't tried out actually sending messages to my list yet.
Someone I'm connected with did just do that, in order to introduce someone he knows & recommended them as a connection (giving instructions on how to connect with this person - who I assume gave him the ok to do so). If you have a connection who knows you well enough to recommend you in a mass email, that may be worth a try just to see what kind of response you get - new connections or maybe potential clients.