This is brilliant, I remember the days of building small PCs/power supplies/bodging rubbish touchscreens/skinning Windows etc - this install has inspired me to emulate it!
How is the GPS performance of the tablet whilst tucked away in the dash? Does it get a decent fix..?
I've currently got a nice (but old) Sony CDX-NC9950 (with the NVX-HC1 navi addon) but I'm going to ditch this in favour of your setup (The MEXBT3900U - hopefully it's compatible with my Sony RM-X2S stalk controller - does your headunit it have a stalk controller input?) - I've just pre-ordered the Nexus 7 tablet (I was going to order one anyway - amazing value at £159 for 8gb or £199 for 16gb) so I'll basically have the same setup, but with the Nexus. Good work!