Press release from Pentax: PENTAX Announces the K-01—a More Powerful Mirrorless Camera
One of the immediate highlights and benefits of this cameras mirrorless body design is its compatibility with all PENTAX K-mount lenses spanning decades. You won’t have to worry and wonder whether an investment in a camera of this magnitude will force you to abandon some of your favored lenses. The fact is this camera was built to be compatible with your existing equipment.
$700+ is a high cost when for a few hundred more you can get a full featured (and not that much bigger) DSLR in the K-5. The fact that the mirrorless camera will use all your existing K-mount Pentax lenses reaching back decades is awesome however. Would much rather it had a viewfinder though, even just a rangefinder style.
Engadget has more here.