I am not sure about the tinker.it Ethernet shield.
Can you provide a link to it? I can't find it. The tinker.it website seems to be down.
If that shield is like the shield in the link, than it seems that it doesn't have the ICSP 6-pin header at the back side. If you have that 6-pin header, you don't need to make modifications.
The older Ethernet shield can be connected with the older Arduino Mega without modification.
The newest Ethernet shield can be connected with the newest Arduino Mega without modification.
I think the code has to be changed some.
Pin 53 on the Mega board is not used, but it must be declared as output to make the SPI work.
I use pin 4 as Chip Select for the SD (both for Uno and Mega).
I use pin 10 as Chip Select for the Ethernet (both for Uno and Mega).
You should start with downloading the newest Arduino 1.0.3.
The unit looks exactly tike the one in the link and it don't have the ICSP socket. (It look like it is part of maker now)
I am aware that the new shield will work without modification on the R3 mega.
Unfortunately the Ethernet shields are fairly expensive here in South Africa for prototyping.And I already have the older shield which I would try and get working.
It is a software fix but all info I found so far are pre arduino 22. The problem is that I cannot find the files that are described in the link and other souses.
Take a look at the schematic of the Ethernet Shield, http://arduino.cc/en/Main/ArduinoEthernetShield
Look for the ICSP header.
The signals are MOSI, MISO, SCK, SS. Those signals are missing, and you have to connect the Mega signals to it.
That is what is done in the link you gave.
Thanks for your help, I have managed to get it working.
I have tested both methods suggested ie. using all 4 pins and 3 pins.
I have the shield contented the following way Mega Pin 50 from pin 12(MISO), Mega Pin 51 from pin 11(MOSI), Mega Pin 52 from pin 13(SCK) and pin 10 remains on pin 10.
Just had to set the pin 53 to an output and it seems to be working. javascript:void(0);