Streak,
The whole idea of SpotWalla (one word) is a method of tracking the SPOT device that a lot of distance riders world wide utilise. It isn't necessarily for the rider, unless you like to review your trip when you get home, but it is a method for the family, or friends to keep an eye on where you are when you don't have that contact. I have found with kids, and a wife that knows what can happen, after her father had some serious crashes, the nervousness of the family goes down when they can log onto the computer and see where you are when you are riding backroads or remote areas.
Don't get a SPOT device and SpotWalla mixed up, as they are two different things and they work independently of each other. You can have a SPOT device and just use the SPOT site for tracking your route, or you can log into Jason Jonas' site (see below) and make yourself a page for people to track your rides/trips etc. You have the ability to put on messages such as taking a break, if you pull over, so any watchers don't think you've crashed, the end of day message so they can relax that you have reached your daily destination, a mechanical breakdown type message that isn't life threatening, or a personalised message for medical emergencies. You can also have these messages sent to multiple phones & Email accounts and personalise which ones go where. For instance I have my break & end of day messages going to my wife and kids phones, and my email & then the breakdown and medical to another FarRider, and ex-copper, as a backup to help co-ordinate things.
The SPOT device is the emergency locator device, similar to a PLB that Abe is talking about, but doesn't need to be changed when the batteries run out if you haven't used it, and if the frequencies are changed again, and doesn't cost you $400 up front. However you do pay a yearly fee for unlimited tracking (I think up to 2000 points are free) after purchase, can use it everyday, change the batteries as required, and you can also send the non urgent message that you can't do with a PLB when in remote areas that you can't use a phone for. I have also lent mine to a mate that went around Australia so his family and friends could watch his trip. Merely logged on and changed the messages and locations sent for that period. Like the PLB you can also carry the SPOT in different vehicles, on your person (come with an arm band) or attached to the vehicle, or in a top-box/tank bag etc. Device costs are now down around $100-$150 if you get it from certain US sources (mate has just done this) and about $150 a year, which some may claim from Tax if you are a remote area worker for safety reasons.
Like a PLB the system is monitored 24/7 from a control room in the USA that has a direct phone link with our National Search and Rescue in Canberra to provide immediate response for urgent assistance. Each device has a serial which is logged so they know who they are looking for like the PLB.
The OzSTOC page suggestion was only if we had enough SPOT owners, it's another way to see rider locations around Oz, and when on rides a safety feature to check if everybody is going all right. The SpotWalla page doesn't cost anything as Jason maintains it free to all users due to sponsorship and a love for what he does. Personally I will be keeping mine, as do many FarRiders.
For anybody else interested in looking:
http://spotwalla.com/index.php Have a look at some of the maps and see what I'm babbling about.
More than happy to answer any other questions. I don't consider myself an expert, just been a user now for several years, and have explained to a few people about it. Some have taken it up, and some have decided a PLB is better for them. This is very much a personal choice, which depends on your own requirements.
Whatever you choose get out on the road and hopefully not test the emergency functions.