My DHT sensor is connected to Digital input PIN2 on the Arduino Duemilanove which I "assume" the Ethernet does not use?
Wrong assumption. The Ethernet Shield 1.0 uses D2 for Interrupt. Try D3 through D9.
In regard to Michael Margolis's book (Arduino Cookbook), there are a couple of programs on page 500 (give or take) of the book. Does anyone know if these time type sketches will be forward compatible with ipv6 whenever it gets fully implemented? I'm not sure that there will be a huge snag issue surrounding the upgrade, but I'm not sure that there will NOT be one either???