From BizJournals.com:
The Federal Trade Commission has issued guidelines that require bloggers or other “word-of-mouth” marketers to disclose if they receive cash or an in-kind payment to review a product.
The notice incorporates changes to the FTC’s "Guides Concerning the Use of Endorsements and Testimonials in Advertising," which address endorsements by consumers, experts, organizations, and celebrities, as well as the disclosure of important connections between advertisers and endorsers. The Guides were last updated in 1980.
Among the changes is one to reflect commission case law that states that both advertisers and endorsers may be liable for false or unsubstantiated claims made in an endorsement, or for failure to disclose material connections between the advertiser and endorsers.