The current iteration of Democracycam is designed to opportunistically join a shared open WiFi network with other Democracycams and automatically distribute any photos taken across the network as soon as they are captured.
This is done in the simplest way I could come up with, using built-in Linux functionality whenever possible and using the excellent Forban software to handle the distribution of images.
Currently the only code provided is for creating a very basic (and not very good) image preview & capture using the Raspberry Pi-based hardware, documentation on the rest of the configuration is yet to come.
At some point other devices & platforms could be supported, but I have some ideas that require lower-level access to the hardware than I think is possible using off-the-shelf devices like smartphones, etc.
It looks like this project has gone stale, but...
What type of network are you creating? You mention both mesh and ad-hoc. The former implies some sort of structure to the network in which there is dedicated routers with devices that come and go at their whim. However, an ad-hoc network connects multiple devices together without the need for structure. If you are using the latter, which I assume is the case since it fits the description, how exactly are you creating the network to allow multiple-hop connections using WiFi? In my experience, it is quite difficult to get multiple devices to connect to the same (truly) ad-hoc network programmatically, at least using Linux drivers. Granted this application seems a little simpler: copy this data to all devices I see.
Also, someone mentioned using a frequency band other than 2.4GHz. If you're interested, you might want to look into a DSSS (or other spread-spectrum modulation technique) that uses random modulation to secure the transmission. 802.11b uses DSSS, but its purpose is more to reduce interference than as a security measure.