A talking cat recently sat next to me on the couch, thanked me for interviewing his creator, and proceeded to tell me a series of dad jokes.  It was the work of a company called Pixi Platforms, which recently launched an iPhone and iPad app that can send the augmented reality equivalent of talking greeting cards to other users of iOS devices. Other featured characters include a talking robot who can play a mean game of tic-tac-toe and Pixi’s newest creation: an envelope that can follow a user ac