At the risk of sounding really old...
There is no way that driving with earbuds in both ears is safe.
At first I saw people with one earbud in and thought "well that's dumb" but then when I got my iPhone, I realized for some of them, it might be their hands free cell phone. Now you can argue that talking and driving is dumb too. But that's not what I'm here to blog about.
Is there something that would require earbuds in both ears? Or is it just people rockin out to their iPods?