The ATF has fired its first shot across the bow (pdf) regarding the Firearms Freedom Act that passed last month in Tennessee. In a letter recently sent to Tennessee Federal Firearms License (FFL) holders, they stated:
The passage of the Tennessee Firearms Freedom Act (…) has generated questions from industry members as to how this State law may affect them while engaged in a firearms business activity. (…) However, because the Act conflicts with Federal firearms laws and regulations, Federal law supersedes the Act, and all provisions of the Gun Control and the National Firearms Act, and their corresponding regulations, continue to apply.
The remainder of the brief memorandum simply reiterates the basic responsibilities of FFL's.
So far, it's just a "friendly" reminder. What happens this winter, when the Act takes place in several states, remains to be seen.