Bloggers too, are now increasingly being hired by companies to be their Brand Ambassadors.
One thing that is in common for such practice to be accepted by the public is that the companies (and now, bloggers) would disclose the fact that sponsorship deals have been made by both parties and that the individuals are considered a Brand Ambassador, or are being endorsed by the companies and businesses.
Robert Scoble mentioned that he was hired by Microsoft in 2003 and was paid to be associated with them.
Popular Singapore blog (http://izreloaded.blogspot.com) is another great example of as the blogger is now being endorsed with a whole range of apparels by a new local high-street fashion shop San Street.
Both of them did disclose the fact that they are being paid and rewarded by the companies they are associated with, and the readers are happy to be informed of the news.
Brand Ambassador IZ Reloaded
Interview with PR2.0 Universe.com
I'm on John Bell's Blog