Communicating location between mobile devices

I am just brainstorming here. Let's say I have 2 mobile devices, iPhone, Android, WinPhone7, BlackBerry, Palm, whatever. I'd like to communicate my location (latitude/longitude) from my device to another one. What is the best way of doing this?

The assumption that each device has either built-in mapping capabilities or a custom-built native app.

I've thrown around ideas like SMS/MMS or email with links embedded in them. However, they all seem to be cludgy.

Any other 开发者_C百科ideas?

A web service (or, if you must and don't care about security, Twitter) that each phone could poll for changes to location might work out. The web service would have to accept the coordinates, obviously, plus be able to be polled for updates by each device. Security is obviously a concern, but that might be another way to go provided that each device had a custom app to accomplish this task as well as web access to poll for changes.

I would go for SMS. It is guaranteed to be private, reliable, low-cost and easy on battery.

Web service is also an option, however:

• privacy is a concern, as the data will leave mobile operator internal network
• reliability - well, you would have to build your own messaging system and that can always fail
• end-user cost - in order to access web service, end-user would have to activate a data session and constant polling can be a source of significant traffic.
• development cost - you would need to develop that web service
• battery life - constant polling over the data connection will have an effect on the battery.

Compare that with SMS:

• privacy - SMS never leaves operator network, so it is guaranteed to be as private as your phone calls are.
• reliability - SMS center is guaranteed to always be there by your mobile operator to accept your messages
• end-user cost - in most networks, SMS cost is negligible
• development cost - well, as SMS center is already there, you can use it without any additional effort from your side (excluding your soft that needs to send and receive those SMSs)
• battery life - no adverse effect on battery

In any case, both devices still have to have a "mapping app" that you can program to interface with the SMS/web-service data.