There was a recent article at The Citizen's Media Law Center on this here:
FTC Seeks to Clarify -- and Justify -- Its Blogger Endorsement Guidelines | Citizen Media Law Project

The FTC FactSheet is here:
The FTC’s Revised Endorsement Guides: What People are Asking

Some interesting highlights:

Q: Isn't it common knowledge that some bloggers are paid to tout products or that if you click a link on my site to buy a product, I'll get a commission for that sale?

FTC: First, many bloggers who mention products don't receive anything for their reviews and don't get a commission if readers click on a link to buy a product. Second, the financial arrangements between some bloggers and advertisers may be apparent to industry insiders, but not to everyone else who reads a blog. Under the law, an act or practice is deceptive if it misleads "a significant minority" of consumers. So even if some readers are aware of these deals, many readers aren't. That's why disclosure is important.

Q: Has the FTC been getting complaints about deceptive blogs?

FTC: No. As it happens, many bloggers and advertisers already are disclosing their ties to each other. Industry associations and self-regulatory groups advocate disclosure, too.

Q: I've read that bloggers who don't comply with the Guides can be fined $11,000? Is that true?

FTC: No. The press reports that said that were wrong. There is no fine for not complying with an FTC guide.

Q: Are you monitoring bloggers?

FTC: We're not monitoring bloggers and we have no plans to. If concerns about possible violations of the FTC Act come to our attention, we'll evaluate them case by case. If law enforcement becomes necessary, our focus will be advertisers, not endorsers - just as it's always been.

Q: Do the Guides hold online reviewers to a higher standard than reviewers for paper-and-ink publications?

FTC: No. The Guides apply across the board. The issue is - and always has been - whether the audience understands the reviewer's relationship to the company whose products are being reviewed. If the audience gets the relationship, a disclosure isn't needed. For a review in a newspaper, on TV, or on a website with similar content, it's usually clear to the audience that the reviewer didn't buy the product being reviewed. It's the reviewer's job to write his or her opinion and no one thinks they bought the product - for example, a book or movie ticket - themselves. But on a personal blog, a social networking page, or in similar media, the reader may not expect the reviewer to have a relationship with the company whose products are mentioned. Disclosure of that relationship helps readers decide how much weight to give the review.

Q: Don't these guides violate my First Amendment rights?

FTC: If you are acting on behalf of an advertiser, what you are saying is commercial speech - and commercial speech can be regulated under the FTC Act if it's deceptive.

Regarding Disclosures:

Q: How should I make the disclosure?

Is there special language I have to use to make the disclosure?

FTC: No. The point is to give readers the information. Your disclosure could be as simple as "Company X gave me this product to try . . .."

Q: Do I have to hire a lawyer to help me write a disclosure?

FTC: No. What matters is effective communication, not legalese. A disclosure like "Company X sent me [name of product] to try, and I think it's great" gives your readers the information they need. Or, at the start of a short video, you might say, "Some of the products I'm going to use in this video were sent to me by their manufacturers." That gives the necessary heads-up to your viewers.

Q: Would a single disclosure on my home page that "many of the products I discuss on this site are provided to me free by their manufacturer" be enough?

FTC: A single disclosure doesn't really do it because people visiting your site might read individual reviews or watch individual videos without seeing the disclosure on your home page.

Q: Would a button that says DISCLOSURE, LEGAL, or something like that be sufficient disclosure?

FTC: No. A button isn't likely to be sufficient. How often do you click on those buttons when you visit someone else's site? If you provide the information as part of your message, your audience is less likely to miss it.

Q: What about a platform like Twitter? How can I make a disclosure when my message is limited to 140 characters?

FTC: The FTC isn't mandating the specific wording of disclosures. However, the same general principle - that people have the information they need to evaluate sponsored statements - applies across the board, regardless of the advertising medium. A hashtag like "#paid ad" uses only 8 characters. Shorter hashtags - like "#paid" and "#ad" - also might be effective.