Arduino w/ Ethernet on a PCB?

Hey there,
I'm not really that familiar with the way shields work or why people use them, I suppose for rapid prototyping as always. I just want to make sure it is possible to create a circuit on a PCB that connects an ethernet port to an atmega 328 that can do some IP stuff like ping, etc. And how does one connect an ethernet to an IC like the one used w/ Arduino without a shield?

If I understand correctly you're wondering if you could make your own PCB that has the same functionality as the ethernet shield? If so then yes its definitely possible. You jusst need to create the proper circuit with a Wiznet W5100 ethernet chip. Here is the schematic of the ethernet shield to give you a better idea what you're up against. http://arduino.cc/en/uploads/Main/arduino-ethernet-shield-06-schematic.pdf

Thanks!
For the curious, found this gem:

Keep in mind that the chip is low cost because it doesn't implent the tcp stack, meaning you'll have to do it in the atmega chip.