Hi there,
thanks for your reply. The Wiznet WZ830MJ board (2nd from the left in the first image in the mentioned blog) looks stunningly similar, however it does have a W5300 chip and a 16/8 bit bus interface (no SPI). I checked the Wiznet page and other datasheets from them but did not find a W5100 module with a similar "two 2.54mm pitch 2 x 14 header pin" interface. Both the amazon article page as well as several seller posts on ebay claim that the SainSmart module has SPI though...
I contacted SainSmart as well as the amazon seller for help on the datasheet but did not yet get any replies- I'll keep you posted.
Having a hard time believing that I am the first guy which actually tries to do something with this module...
Cheers Blueish