This was just announced at the cell phone show in Spain:

It's quite small but if it can be hacked might make a great control for audio playback for a car PC.

I've been looking for a way to add a car PC and expand the audio in my Ford 500 but the steering wheel buttons and dash modification (probably Kenwood touchscreen DVD player) have some huge disadvantages (time, cost, increased theft possibilities...)

The original Ford system does include an auxillary input. My idea is to hack this little bluetooth touchscreen and have it talk to a small PC mounted under the rear panel. The PC would send audio from its hard drive via WinAmp (RockSteady compressor is very nice into the dash unit which then feeds into a CleanSweep ( because the factory speakers are pretty good for mid and high and an added subwoofer .

The PC will also have a wireless G router and a USB 2 booster/extension to one or more hubs (glove box, center console, dash compartment, I'm not sure yet...) for memory cards, cameras, disc burner, keyboard, etc. Cell phone tethering would give Internet access while driving. Anyone in the car should be able to use bluetooth or b/g to have net access and updating the software/data could be done while the car is in the garage (assuming an extension cord is used to provide power so the car battery isn't drained.)

I've found the in-dash GPS is unsafe compared to a display at the windshield level. The 3.5" windshield-mounted GPS units work quite nicely. If a larger LiON bluetooth touchscreen could be had, perhaps it would be possible to add GPS display and some other functions (gas purchase log, email alerts, tickers, handsfree with auto-pause/mute of the audio if a microphone is added, etc.)