Shoutbox

It is possible, even if you are chatting to different people at the same time, (DP's are send each time a contact's client requests it (eg: starting a convo, or if the DP changes when a convo is open)).

But it will require a lot of "programming and tweaking" (current normal DP sending must be filtered out, and each time a client requests a DP, the plugin/addon should block the request to be send to MSN Messenger and send his own DP instead => proxy)

And as this can only be done by "tampering" with the protocol, it will NEVER be included in Messenger Plus! itself.