[Openstreetmap] OpenStreetMap/Freemap and mobile devices?

[Nick Whitelegg]

A thought I've had for some time with Freemap, wouldn't it be good if OSM maps 
could be displayed on mobile devices like PDAs or even phones? Without a lot 
of knowledge in this area ATM (but am keen to learn) I'm not sure how 
feasible it would be but the following appear to be true:

a) the device would need inbuilt GPS;

b) There would seem to be two ways of implementing this:

i) Get your current position from the inbuilt GPS, construct an HTTP request 
to the server using, e.g. the cURL library, and get a map back as, say, a PNG 
image.

ii) Send an XML-RPC request to the server, get the raw data back then process 
the data to draw the map on the mobile device. This is more flexible but 
requires more processing on the device.

c) the device would need to make a request to the server every x minutes or 
seconds, or when the position has changed by y metres/feet.

Doubtless there are many practical problems with battery life, etc, but it 
would certainly be something worth investigating. I also gather that most 
mobile devices cannot connect arbitrarily to the internet through 
user-written software, for security reasons. So (correct me if I'm wrong) it 
would only be possible to do this sort of development under the Linux/Qtopia 
environment at the moment and not under Symbian or Palm environments.

If this is feasible it's certainly something I would like to get involved in. 
Are there suitable PDAs out there with GPS ability, or could I get a cheap 
pluggable GPS unit and plug it into an arbitrary PDA?

Thanks,
Nick