Walt Mossberg has had a look at the SPOT satellite messenger, a GPS gadget aimed at adventurers and thrill seekers. Not only does it call in the emergency services if you're stuck and there's no phone tower for miles, but it also sends out position updates to keep friends back home updated on your expedition. It locates you via GPS, and transmits data by satellite to a control centre, which routes messages on for you, and its three buttons couldn't be simpler—"OK/Check," "Help" and the one you'll hopefully never click, "911." More juice below.
Waterproof, floating, altitude-proof to 21,000 feet and freeze-proof to -40 degrees Celcius, its bright orange case is about the same size as a BlackBerry, and it's powered by two lithium AA batteries.
Its simplicity rests on an annual service charge and front-end website: through this you can send an unlimited number of GPS position updates to a list of buddies for US$100 a year, though you have to pre-arrange the messages since all SPOT itself has is those three controls. If you do need to call in assistance, it prioritises that alert and repeats the message until its battery is dry (about seven days). But since there's no way for a message to get back to you, it might be a long, hard wait.