Psiloc Where I Am for SE P800/P900
...Locating of the device is based on the GSM network cells, but it is not visible. You only have to �teach� your phone the important locations like home, school, work, best friend, train station, church etc. This is very easy and doesn�t require any technical knowledge and understanding. It can be done from the Location menu.
However, the best of all is that you can create EVENTS!
Once there is at least one location saved you can create events for this location. Currently Where I am offers three event types: Alarm, SMS and Start application. That means, you can create an event to have an alarm at the moment when the phone approaches (or exits) selected location (geographical area). So you will be able to sleep in the train to work � your P800 phone will wake you up precisely at the desired station, even if the train is late. It can also be set up to remain of the speed controls!
The automatic SMS sending event can be used to inform your wife of coming back from work or to notify the coworker that the truck is coming to plan the work more effectively etc....
I haven't tried it yet...looks interesting though