You might consider it a high-end successor in the mobile space, but the BeagleBoard has really grown far outside just a low-cost development board for mobile application software. I don't believe the PandaBoard is geared at having the same reach into new device types and to hardware hobbyists---but if what you are interested in is getting the ability to develop mobile applications and application stacks cheaper and earlier than buying closed mobile phones, the PandaBoard might be just right for you!