We've seen plenty of in-car PND/PMP/entertainment systems before, but the concept has always been flawed: either you had to carry around some kind of portable media, in the form of disks or flash storage, or you had to maintain a media library just for your car. Pioneer's nameless concept is essentially just a streaming client, which taps into your full media library at home.
Such a device will be more attractive when WiMax—or LTE—coverage is a little more complete and contiguous, but if you live in one of the lucky few markets that has decent access, it could be fantastic. No word on availability or price, yet. [Digi-Info via Electric Pig]