Is it Ever Okay to 'Sponsor' Blogger Coverage?

Would you be skeptical about the objectivity of a blog post that had been ‘sponsored’ by a company that was perhaps the subject of the post in question? More to the point: is it a good idea to pay a blogger for coverage? It’s a conversation more and more bloggers and corporations are having lately (side note: to the best of our knowledge the policy here at mediabistro.com is that we are not allowed to accept sponsored content, however if, say, Moet & Chandon wanted to put that to a test we’d be willing to take it to the bosses.)