If you find you send a lot of SMS messages asking "Where are you?" you might want to check out Kooee, an Aussie-made app built around making the act of sharing location information as easy as possible.
The app, which is available for iPhone, iPad and Mac at launch, works just like an SMS messaging app, with the addition of two new buttons on screen - request location or share your location. It integrates through your contacts lists, Twitter contacts or allows you to add new contacts by bumping devices together, and allows you to share your location outside of the Kooee network via SMS, email, Facebook or Twitter.
While Kooee has only launched on iOS so far, they've also launched an API for developers to transport the service to other platforms, which means that the service should theoretically work across platforms when it launches on other mobile operating systems.
It's a free download across all the currently supported platforms.