The fusion of web services and desktop software is a holy grail of computing bliss that few can claim. Anyone who has ever gone back and forth on whether to use the convenience and innovation of Gmail on the web vs. the power and integration of a desktop email client like Apple's Mail.app knows what we're talking about. While the melding of these two universes might seem like an impossible hope to some, Mailplane is a new desktop Gmail client in private beta that just may be a light at the end of the tunnel.