Bloggers as advertisers

The standards to which we should hold bloggers was briefly referred to in this blog last year. When bloggers comment on issues, should they disclose any potential conflicts of interest? Should blogs be allowed to be set up as appearing independent, when they are really an advertising tool of a company? What legal issues (in the Australian context or elsewhere) may be raise in such a situation?

Some of these issues are covered in this article from the New York Times, "Wal-Mart Enlists Bloggers in P.R. Campaign" (free subscription required).