Hi All,
Answering my own questions here in the hope to help others that read this thread.
I noticed that there is a dev_udp branch over at GitHub - arduino/wifishield: Arduino Wifi Shield which I can confirm works very well with UDP. It will require that you update the firmware on your wifi shield and replace the library ( this includes a new example WifiUdpSendReceiveString ) in your arduino ide installation but nothing overly difficult.
Hope this helps,