I think that you should be able to communicate with people if they are on a different SMP. You could make it a supporter perk and only between friends. Basically, you could do a command, similar to /tell or /msg that allows you to talk to your friends that are on a different SMP. This could come in handy because there have been many times as of late where I want to talk with some friends, but I need to work on something on a different server. If we could talk to each other through some kind of chat system, that problem could be solved. I'm not sure if it is feasible, but I think it would be sort of like the messages you get when a friend connects to a server that you're not on. Anyway, it's just an idea. Let me know what you think.