Not sure what homebrew efforts are about these days -- most were for closed source protocols that likely have long since changed and rendered them incompatible, and it is not like open source chat protocols from then do particularly well today either (don't think there was a XMPP chat program worth noting in this). Most will also not do much with images and be all about text instead.
In the commercial world then "ping pals" is what most would have looked to but I have no idea if that works over the wifi replacement services (it would likely be more involved than the basic matchmaking efforts from those).