iPhone OS 4.0 has within an application that, when hooked up to a video out, shows this kind of user interface. After digging around through some APIs, like ones named IAPSimpleRemoteCarButtonNotification and IAPSimpleRemoteCarButtonTypeKey, we’re led to believe that these iPod Accessory Protocols will enable car accessories for music control. Another hook would enable handsfree commands, so it looks like combined with some simple directional input, you’d be able to handle all of your music navigation while behind the wheel no problem.
Of course, we haven’t seen anything like an Apple car kit yet, but the possibility is clearly there. Hopefully iPhone OS 4.0 will play nice with stuff like the Ford Sync and Chevvy Volt, but we’ll have to wait until it comes out this Summer to know for sure.