I have a few mr3020 lying around and was thinking of using their wifi to build a wireless mesh (2 mb/s speed are achievable with a mesh network), and the expose serial gateway over an ip port.
SoC: Atheros AR9330 rev 1
802.11 b/g/n 150 Mbps
Powered via USB B-Mini (5 Volts)
Tiny form factor
5.7 cm x 5.7 cm PCB
6.7 cm x 7.4 cm x 2.2 cm case
This would allow the nodes to be wifi-capable and only one node would have to be tied into the lan. It would make the WAF (wife acceptance factor) increase tenfold at least

. And i would rather spend 15-20$ for a mr3020 instead of 10-15$ for an ethernet module.
On the other hand, using an ethernet connection to the mr3020 and using the mr3020 as a bridge only would remove the need to write a serial-to-usb interface on the little router.
Darn, i've just finished making a pcb to plug the nano and everthing else and bought a case... back to the drawing board again...