Glad to hear you've been happy with JFBConnect so far. While we always love upgrades, older versions of JFBConnect work as long as Facebook doesn't change too much, which currently means that 4.0.x releases should have no big issues, and we expect it to continue working for at another 6 months or so.
As for your question, no, there's no way to post to user's friends walls.. not built into JFBConnect at least. We did just add the new Requests feature, which sends notifications to individual users, but it's not a public invitation.
As far as I know, there's no way through the API for a user to post to other people's walls like you're looking to do. Status updates for the user can be seen by their friends, obviously, but Facebook makes it hard to really 'push' into other people's walls for obvious privacy and spam reasons.
Hope that answers your question, but if not, let us know!
Thanks,
Alex
Invitations on friends' walls
