IPv6 enabled carriers?

Does anyone have a list of carriers who are IPv6 capable today? I would assume this would be rolled out in larger cities first but anything outside of "testbed environments" and "trials" as in Comcast's recent announcement seems to be all that is available. I'm being tasked with coming up with an IPv6 migration plan for a data center. Mostly interested in if ATT, Level3, GLBX, Saavis, Verizon Business and Qwest are capable as those are the typical ones I deal with. Thanks...Chuck