The member list is growing fast, but, unfortunately, lots of those members don't post anything...
It's been a while since Patchou was here (the last time he logged in was May 6th)... I wonder what he's up to...
I was planning to e-mail him soon and tell him to update the Interactive Agents for the new version of Messenger. I'll also tell him about this thread and maybe he'll post a reply.
About the open source thing... it's not a bad idea, but Patchou has said that he doesn't want to do that, and it's his decision, of course. Maybe letting someone else (or a group of people) continue development is the best option. With open source, there might be many different versions of MsgPlus, and you wouldn't know which to use and trust.
Hopefully, Patchou will find the time to add more cool features, and a change of developers won't be needed.
I agree that Plus! is the best Messenger addon available, and it becoming abandonware would be bad.