I have the same issues, but I'm using the correct library!
This hardware: http://www.ekitszone.com/p/11/enc28j60-ethernet-shield-for-arduino-uno-duemilanove
This library: https://github.com/jcw/ethercard
I'm setting with a third parameter, because this board uses pin 10 and not 8:
if (ether.begin(sizeof Ethernet::buffer, mymac, 10) == 0)
Somehow though the code does not execute after this if statement... the leds in the socket blink, there is nothing else connected on the board and I'm using an Arduino Uno with Arduino software version 1.0 on OSX.
edit: To clarify, I also tried setting a static ip, but no luck either...