Okay, so forward this off to the right place if this isn't the right place to ask this question.
I want to use a tablet computer as a car-computer. Minimum features would be to run my music (through iPod, Pandora, whatever I want) and GPS Navigation, watch TV or movies while I'm parked waiting for people, and the hard one: it needs to answer my phone calls with a pleasant interface much like in-dash systems do. It needs to detect that my phone is ringing in my pocket and provide an on-screen answer/ignore and then route the audio through the cars speakers. It would be nice to dial out and have address book access, but that is somewhat secondary.
I have an iPhone myself and I figured that an iPad with 3G might make a good system for this - but I'm open to other options if an iPad can't do everything I need. I'm willing to write code, and I'm willing to jailbreak one or both devices. I haven't done much work in Obj-C, but I'm not opposed to learning a new language for this project. It's self enrichment for the most part, as I'm sure I can buy an indash entertainment system for less.
Does anyone have experience with the iPhone/iPad SDK that can tell me whether or not it would be possible to get it an iPad to answer my calls in the car? What about an Android tablet? (that Adam looks promising, too).