The german surplus vendor Pollin offers an Atmel 32 based Ethernet board:
Atmel 644 is pin compatible to Atmel 32. The 644 is also known as Sanguino and should work with the Arduino IDE. So if you use this board and replace the processor you have the desired result.
I am not aware of an US vendor for this board but I would expect that these boards are availabile somewhere else as well. As far as I know Pollin never manufactures on its own.
A similar but smaller and more expensive module can be found here
Udo