Yahoo recently launched Fire-Eagle, which is essentially an 'open platform' that allows two simple things:
A) Users can update the system whenever they want with their location
B) Application Developers can access the system whenever they want to know the location of consumers and do anything with it (i.e. serve any application that can make use of that information)
Of course, 'Users' can explictly set permissions on who can or cannot view their location.
For a long time, I have wanted to see such an open and simple platform, where 'executing a service based on location' is completely independent of 'the technology used to provide the location'. Because I believe providing individually accessible repositories of data is the key construct to building a hierarchy of innovative products. You collect data, expose it to others so they can transform your data into information. And your information, is data for the next application. So turns the wheel of the Web 2.0 circle. And a location repository is one key missing element to personalize services.