From an article in the Chicago Tribune on Mommy bloggers but I think it will apply everywhere:
The Federal Trade Commission has begun reviewing its advertising guidelines with mom bloggers in mind.
"Those who are compensated to promote or review a product" on their personal Web sites "are not exempt from the laws governing truthful advertising," said Richard Cleland, the FTC's assistant director of advertising practices, in a recent statement.
An ARC would be compensation, right? And if a third party is getting paid for your review, well. This bodes watching.