I've been thinking for a while about a system to broadcast the runners GPS positions live during a race. Nowadays, things are getting more and more simple for three main reasons: the integration of GPS in mobile phones or the easy connection via BlueTooth, the possibility to program mobile/satellite phones, and the simplicity to broadcast positions over the internet via tools such as GoogleEarth. There is no need for a PDA to link the GPS receiver and the mobile phone anymore.
On races such as the UTMB (r), mobile phones will be out of coverage. Therefore satellite phones seem to be the key. Most of them include a GPS as well (*), and embed a decent operating system. I was thinking to buy a cheap second hand satellite phone for that purpose, but they don't seem so cheap :-/ Even more expensive on ebay than through regular retailers... The other issue is to write the application that will get the GPS position every 15 minutes and send it though the satellite link via SMS or HTTP, the latter being easier if available. In order to use all the specific functionalities of the phone, a SDK is probably necessary. I've not found any for Thuraya phones for example.

Can anyone help me with one of these two points: where to find a cheap satellite phone and how to develop on it ?

Ultra tracking.

(*) this is not as obvious as it may seem, as satellite phones and GPS devices use different kinds of satellites and technologies.