After market car stereos with iOS 4/iPod Out support?
iPod Out, indeed, looks very cool ...

http://www.youtube.com/watch?v=Wbco58GnS9c

... but is there any reason that a simple line-out cable wouldn't work, at least until more companies hop on the iPod Out bandwagon? There appears to be a whole lot of nothing out there right now.

At the very least it's way better than the FM transmitters, which really suck.