This is really cool! But also kind of complex for a task that could be performed in a much simpler way. Using a GSM module such as the Telit GM862 [1], you will be able to receive text messages directly on the Arduino without the need of any web services. This would be much faster and cheaper. This particular module even includes a GPS. [1] http://tinkerlog.com/2009/05/15/interfacing-arduino-with-a-t...
a GSM module requires you to deal with cell phone companies for service though, right? i'd much rather integrate with twilio than with bell.
Personally, my comfort zone was with web development and I had the WiFly handy so I used Twilio and Pusher - worked out alright :)