You can get IPv6 DIA from them, but not IPv6 TIC. They are not the same. All of the agencies that moved to provider-based TIC cannot get IPv6 service in time for the mandate.
Some people are saying, "Yeah, providers will give you IPv6 addresses for your DIA circuits. I don't see an issue." But they aren't fully aware of other mandates that influence civilian agencies' abilities to meet the IPv6 mandate. Namely, this one: http://www.dhs.gov/trusted-internet-connections-tic. None of the TIC provider's are offering IPv6 connectivity that I'm aware of, but they are all in various stages of getting there. The agencies that are ready most likely host their own MTIPS offering or (more likely) using hosting companies to get there.