While I agree that 411 is a great keyword (almost 300K Ovt searchs and almost 100K for the .com!!), I don't know about "dial411". Plus it doesn't make much sense on the internet. Maybe type411.com (which is still available) would be more applicable.
Not a bad name, but I think 411.xxx will be all the traffic. If you're planning to develop it and build around the great 411 keyword that I could see it being worth low to mid $xxx. :imho:
Good luck.