I was looking at starting up a site that would sell bitcoins through credit card transactions as a US based business. Not wanting to run into immediate regulatory problems I gave FinCEN (Financial Crimes Enforcement Network) a call. It took them a couple of weeks to get back to me but the answer was yes that business would be required to register as a Money Service Business.
I can only see that if you buy and sell them on the same site. If you are just selling them there should be no need for that. Bitinstant is great example why. Reason being you move funds to and from your bank account. If funds are just moving one way it should not be any problem to them as long as you pay your taxes. I recently started selling coins for credit card and that's the answer I got when I called.
I have talked to the Attorney General office and the S.E.C.
When exactly did you call them?
Did they state exactly why?
were you going sell and buy coins?
I mean credit cards are easy to monitor its bank transfers they are really worried about.