GPS has gone to the dogs ...

At $199 for a unit, it's a bit pricey, but ... it's probably worth it. Of course, there is the monthly service contract too.

Then of course there are the other GPS-for-your-dog systems:
1. GlobalPetFinder, which you can supposedly buy for $289.99 (which I cannot confirm since their webstore it broken).

2. RoamEO Pet Location System, but the damn thing is almost $500 and only has a 1 mile range. Nevermind the battery-life is about 8 hours, so if your dog goes on a nightlong jaunt ... you're both screwed.