One link-building tactic for sites with deep pockets has been to pay bloggers to review your offerings.
A recent Guideline issued by the US FTC may impact on how this kind of “advertorial” can be used in blogs and websites. In particular payments may have to be disclosed:
The FTC will require that writers on the Web clearly disclose any freebies or payments they get from companies for reviewing their products. The commission also said advertisers featuring testimonials that claim dramatic results cannot hide behind disclaimers that the results aren’t typical.
http://www.msnbc.msn.com/id/33177160/ns/technology_and_science-tech_and_gadgets/