Unexpected visitor -- Anyone know him?

So I was at the computer catching up on some emails before going to make dinner when one of the boys says that there's a dog at the door to our deck. Figuring that it was just one of the neighbor dogs I didn't think much of it, till I got over there and discovered this little guy scratching at the sliding glass door...



We're calling him Jack till we find out what his real name is, but he seems to like it. His tail is clipped and he had a collar on fairly recently, can still see the indentation in his fur around his neck. He's quite friendly and settled in pretty well after Frank (one of our cats) stopped stalking him, though whenever Frank shows up he's still quite intimidated. Hopefully Jack has a loving home out there waiting to welcome him home, cuz I really don't think that our house or family is ready for a dog.