Arduino nano with ethernet and PoE

I'm aware of the Freetronics etherten which married arduino with ethernet and PoE, but has anyone made a nano version of this?

My project calls for the smallest implementation of Arduino with ethernet and, ideally PoE, so that the whole bundle may be placed in a light switch back box with limited space.

I'm also aware of the cheap (c. $15) nano ethernet shields which look good but (a) don't implement PoE and (b) are not integrated into the same PCB as the nano.

Also some of the latter feature the ENC chip rather than the full W5100 chip which supports TCP (a must for me, because software TCP is too expensive, memory-wise).

I imagine a nano combined with ethernet chip will probably not be possible on a PCB package the same size as the nano on its own, but a slight increase in size is fine.

If I can't find the above I would consider having my own version made, in which case are the nano and wiznet schematics / pcb cad files open source such that I can download them and have a go at combining into one package myself?