Connect One Ethernet shield

[dhouston]

Why the offset square pads?.

The diamond shaped pads are those that the user will likely need to solder in wire jumpers to make connections for pull-ups, set the address, etc.

The slightly askew square pads can be used to reroute the IO lines if needed. Cut the trace between pad and the sockets at the board edges and run a wire as needed.

The octagon pads are those which are unused for the hardware setup.

Round pads are in use by the hardware or hidden beneath the sockets.

The one on the left above the I2C eeprom looks like a recipe for disaster (from a home-brewed PCB perspective).

I'm not sure how. If you mean for those who make their own boards, I think these will be available with all of the etching, etc. done and even with most of the SMT components preinstalled. The one I think you are referring to is for installing a jumper in case a pull-up is needed on the serial line - I just forgot the pull-up.