Weary travelers at San Francisco International Airport can now while away time at the terminal by cavorting with black Labs, Saint Bernards, terriers and other specially trained therapy dogs. The dogs, introduced by the Society for the Prevention of Cruelty to Animals in early December, are meant to cheer the homesick, the aggravated, the fuming and the just plain bored. Accompanied by their owners, the pups trot through the airport wearing vests reading "Pet Me" in hopes of meeting new friends and experiencing many fascinating new smells. SFO is not the first airport to let the dogs in. Airports in...