We've been talking about this over here but I thought it might be worth mentioning it in the forums as well.
I'm working on porting the driver for the WIZ810MJ ethernet module to a form usable in the Arduino. A couple of other people are working on a PCB breakout board for the module as it uses non-breadboard/protoboard-compatible 2mm pitch headers (instead of the usual 0.1"). I've been using 2mm pitch jumpers salvaged from a floppy drive or you could also try 2mm pitch IDC ribbon connectors/cable.
You can track my Arduino and WIZ810MJ ethernet module progress here but the current state is I've got it working with ported driver routines enough to be a simple echo server that sends data okay but has some problems with receiving it. The data's received okay, it's just a matter of accessing it.
Example source code and (currently only) binaries of the library files are linked from the page.
The reason why this particular module is of note at the moment is that Circuit Cellar and WIZnet are currently running a design competition and are (presumably, still) handing out a sample module if you request one.