The PetsMobility PetCell is only a concept for now, but the patent-pending collar could be great—if you don't mind spending a lot of extra cash on your pets. The idea is simple: it's a cell phone and GPS unit on a collar, with its own private number. Using caller ID, it automatically picks up when an approved number calls, allowing you to speak to your dog or cat (but probably dog) from wherever you are. And with the GPS service enabled, you'll even be able to yell at them when they've wandered too far from home.
No word on an actual shipping product yet (their first announcement at all was in September), but it looks like something that could be surprisingly fun and useful for people who will spend any amount of money on their pooch.
Product Page [PetsMobility]