Location based applications for android

I would like to develop a location based application for android. I have been writing some code and succesfully retrieve my current location.

The thing is that i would like to be able to handle another people locations too (of course once registered in my service and accepted the terms of service).

I am not sure wether is legal or not, but, which would be the best way to develop locati开发者_C百科on based applications?

Registering people in my service and handle latitude and longitud myself or maybe should i use the google latitude API? I would like to know the best approach in these cases.

I would build (and I did :)) own service for handling users' location. In case you will try to use google latitude you have to push your users register not only with you, but also with google application....