StumbleUpon has finally released its mobile apps for the iPhone and Android. "Think about all those times when your'e riding the bus, sitting at the airport gate, or waiting for friends, playing with the same mobile apps again and again," says StumbleUpon's mobile apps team. "Now you can have the perfect boredom-buster: with StumbleUpon for the iPhone and Android, the best of the web is, literally, at your fingertips." "Following the success of our iPad app,