Android does boot quite slow. ChromeOS addresses that issue by basically using MeeGo developed fast-boot technology. Also, millisecond boot times aren't possible unless they are referring to resuming from some sleep state.Lingering objections to Android appear to boil down to two issues, according to a Freescale executive at the Technology Forum: boot time and versions. Android can take as long as 40 seconds to boot, as anyone who owns an Android phone can attest. Android supporters say the millisecond boot times required by automotive specifications can be achieved with hardware and software workarounds.
They also claim that the issue against using android because of versioning issues is moot. The fact that android is driven by google (or if you want to believe an actual consortium of members) for handset applications *only* is an issue that isn't addressed.
Anyways, enough android bashing. This story is a good sign that OEMs are very interested in the app store idea, but its much more complicated than a handset app store. Nokia seems to be taking an interesting approach with their "Terminal Mode" project. In their approach, the car is just a dumb-terminal to the phone. It'll hook up with the phone when the phone is in range and display the phone's interface. In this scenario the lines between handset and car applications are very blurry.
Mp3car's app store is a step in the right direction. I hope it'll take off and in the future, become more integrated with the carPC OS (which, IMO, is paramount).