Sorry that I didn’t notice this thread yesterday. Since the first version of OpenSprinkler,Ethernet Jack has been changed a couple times to reduce cost: initially Pulse J00-0061NL, then SparkFun’s Ethernet jack, and now Hanrun HR911105A. Unfortunately these jacks have very different pinouts, so it’s important to know exactly which part to use for each PCB. Particularly, the extension boards are sometimes using undocumented PCBs. If you need, I can send you the schematics, but in general I don’t provide part number or build instructions for undocumented PCBs.
The Dec 2011 PCB uses SparkFun’s Ethernet jack: https://www.sparkfun.com/products/8534
Hope this helps.