While looking at the design of the OZ7IGY beacon I noted they were using a GPRS shield to remotely manage the beacon via cellular http://rudius.net/oz2m/ngnb/management.htm. I could see all sorts of applications for the system. I looked at the module they were using and decided it was too expensive to play with and looked for cheaper alternatives. I came across the EEGTECH WGW-06633 which was only $33 but did have audio in and out so I ordered one.
A few weeks ago I came to the conclusion that there was no point in doing RSGB 50MHz and above contests without having access to ON4KST. After consulting with G4BVY I bought a Huawei E5330 cellular to WIFI converter and got the cheapest cellular plan I could find from giffgaff which would give me 250MB of data and 200 minutes of phone for 7.50 a month. They also supplied the sim. O2 were the carrier, which was unfortunate as they have awful coverage around here, but it was worth a try.
The internet revealed a very useful tutorial at http://www.seeedstudio.com/wiki/GPRS_Shield_V1.0 This has examples for making voice calls, sending sms, receiving sms and reading html files all of which worked fine.
The ultimate test that I achieved was to have my shack PC monitor 10m wsjt JT65B signals and upload the decodes to my web site. The arduino and shield recovered these spots from the website and sent an sms of them to my phone. I can see some useful variations of these scheme being deployed on a long term basis