Paul,
There is a company called Connect 1 which makes a serial-WiFi device. It does take 200mA at 3V. The link is:

http://www.connectone.com/products.asp?did=73&pid=98

I'm going to give them a call on Monday.

The link below makes a device for connecting to your car's computer wirelessly via an iphone. pretty cool. It certainly can be done.

http://www.plxkiwi.com/kiwiwifi/hardware.html

Eric