Several bloggers, the only one known to me before Alex Halavais' post being Elizabeth Lane Lawley at mamamusings, are making money by writing about a certain company. Once a week they have to write about this company and link to it.
To me, the idea of getting paid for what I write here is of course tempting - I would love to be able to live from it. But I have worked as a journalist, I have lived under editorial restraint and I have written in order to make certain the paper has enough readers to attract enough advertisers to make the budget balance. It's not what I do. If I wanted to satisfy advertisers, I could have a job in a women's magazine or a big news paper. I chose differently.
Making money from your blog changes the model you work within. Getting paid to blog changes the blog. It isn't personal publication any more, your blog has become a one-person business.
I think there is a difference between the practice of Christopher Allbritton, who went to Iraq sponsored by his readers, several individuals paying an individual, and Elizabeth Lane Lawley blogging about a certain product each week in order to get paid. Allbritton was paid to write more of what he already did and from a better vantage point, Lawley is paid to write one particular thing once a week, adding a link and thus manipulating google rank.
A significant part of Lawley's trustworthyness comes from her position as a scholar, an academic. It is what has made her blog important in the development of blogging, and what has given her a considerable part of her recognition. Yes, she is brilliant, but she is also positioned within a system which supposedly is not commercialised and thus should be independent of other interests but the public good. Although it may not be, what do I know - there are horrible stories about sponsored colleges reaching the protected, public educational system of Norway. Still: it is her status as a scholarly blogger which will sell a product.
Paid research is already a problem in Academia - reports being altered, held back or buried if they do not please the parties paying for the research. We know it happens, no matter how the idea makes individual scholars shudder and mutter: "but my path is clean." Now we get promotional academic blogging. Fun.