Arduino UNO + Arduino Ethernet Shield - can't read SD card

Digital pin 4 is the SS for the SD card. Try this in your setup() routine:

Serial.print("Initializing SD card...");
  // disable the ethernet SPI
  pinMode(10, OUTPUT);
  digitalWrite(10,HIGH);

  // SD card SS pin is digital 4
  if (!SD.begin(4)) {
    Serial.println("failed!");
    return;
  }
  else
  {
    Serial.println("ok");
  }

edit: change bad spelling.