SurferTim:
Holy cow! Where have you been? If this is an ethernet shield, digital pin 4 is the Slave Select pin for the SD SPI interface. Sometimes I wonder why I do this...
If there is nothing connected to pin 4, where does the trash come from? I have an older ethernet shield so I can't do an actual test, but from what you say with a new ethernet shield has issues with pin 4 being used for anything but an spi interface. I currently use IDE1.0-rc2 and have no compile errors. How does any connection to pin 4 impact compiling the code?