I would like to dig into developing for jailbroken devices, just to test what the device could do. I would like, for instance, to alter the ipod music based on geo-location, so i have to program a new daemon that runs in background and fetch gps informations at regular interlavs and then make something with them.

Longitude, longitude, for instance, does exactly this, even when the device is locked, and then upload the informations on google latidude.

I have some experience as an iphone developer, but i'm not sure on where to find documentation to accomplish such a task. I know about the books "iphone open application development" and "the iphone developer's coockbook", but i don't own them and i'm not sure they have what i'm looking for.

Any advice on this?