T-Mobile’s FamilyWhere app offers both free and paid versions of its tracking service. FamilyWhere Check In is a free service that allows kids to manually send text message check-ins with their location.
FamilyWhere Locate costs $9.99 for up to 10 lines and adds additional functionality. Under this plan parents can automatically locate the other phones on the plan as well as schedule automatic location checks.
Of course, FamilyWhere only works when the phone is on and in a T-Mobile service area, so the old “movies” dodge should work just fine for teens looking to circumvent the system. You know, because it is very rude to keep your phone on during a film. *wink*
source: Android Market via Engadget