INRIX, a major data provider to most GPS brands offering live traffic in the U.S., announced today that they are bringing live traffic coverage to the entire U.S. Interstate highway system and to many rural highways as well. You should be able to see this on MapQuest if you want to test it out. I'm not seeing anything in my neck of the woods, but hey, maybe there aren't any incidents today.
For the time being, only incident alerts will show, but INRIX expects to add historical speed data this summer. I can't wait for that. Maybe I'll end up buying a Dash after all.