Ability to send text messages in a large mesh-network at least would be useful and many would willingly join such a network because the data amounts relayed would be minimal. P2P GPG-encryption of the messages should be implemented also (compression comes along implicitly then). Multicast and broadcast text messages in some restricted way could be supported also.

What I was talking earlier, the mesh network like this should also be able to use GPRS/UMTS-data to relay then when next WLAN-hop is not found. Mesh-network participants could enable and disable the feature acting as a cellular-relay and maybe also select if they are willing to relay only text messages or voice also.