I don't think the govt would arrest you for accepting bitcoins, at least not only you.

They would come out and say that bitcoins are now illegal, and stop it for everyone (as if they could), rather than singling you out of the blue for arrest.

However, they could go after you specifically if they had some vendetta against you, but they would go after tax fraud, i.e., that you hadn't adequately accounted for your capital gains, or you could be audited into oblivion.

They arrested the liberty dollar guy because his coins had visual similarities to US currency. I think they said "In God we trust" or something on them. Bitcoins definately don't have this problem. But accepting an alternative currency in and of itself is not illegal. but they might be able to dig up just about anything else if that's their intention, as previously noted.