Zoombak

All I can say is "finally"-there's now a long range GPS tracker for dogs.

Zoombak is a lightweight collar attachment.  If your dog leaves what you've defined as a 'safe zone', you'll get an instant e-mail or text message letting you know that Lucky has left your yard, and is heading down Oak Street.  You can use your cell or internet to get location updates while you track down your dog, and they provide 24/7 customer support so you can get your pup home safely.

The unit is waterproof, and comfortable for most dogs over 15 pounds.  A long-life battery requires a recharge every 5 days or so, depending on how many location requests you process.  Fortunately, the unit will send you a notification before the power runs out. 

The unit itself is $199, and a monthly service plan starting at $9.99 is required.  It seems pretty reasonable if you've got a dog that loves to wander, especially after watching their demo video...