Indeed - I've been meaning to experiment with a GSM module actually, I just had the WiFly handy so I built it with that instead. One thing I would say is that using the WiFly allows you to connect with web services as well as the cell networks (in my example I made a very basic Sinatra app with an on/off button)
It's definitely also a good argument to just use what's in hand!
It is actually also possible to connect to the internet using that module, using good old GPRS (The module contains a full TCP/IP) stack. Of course not near as fast as an average wifi connection.
I used it to create a set-up where you can send a text message to the module: "Where are you?", it would then respond with the latitude and longitude as well as the geocoded address using Google Map's Geocoding API over GPRS.
The Telit module is fully on the internet just like your PC. The module can do GET's and POST's directly to any server - no extra host needed anywhere.
