We wanted to share this with everyone: we are announcing a new WIFI shield for the Arduino. The shield is based on the Gainspan GS1011 module. The shield is fully assembled and comes with pins 10-13 jumpered, but if those conflict with something else on your project, you can re-jumper the communications pins to 4-7.
We worked out an extensive library with a bunch of examples to make getting started easy, with twitter, webserver and client, and TCP/IP, WEP, WPA2 examples already worked out as well as a library to use some of the more common functions.
You can see the shield homepage here: http://www.dexterindustries.com/Arduino-WIFI_Shield.html
And you can see the wiki we setup, with examples, here: http://dexterindustries.com/manual/arduino-shields/arduino-wifi-shield
The shield costs $75.
I would love to hear your thoughts!