I dont see why not, good a use of the blogs as any. I think there will have to be rules though, something like only one advertisement per week per person or something, or you will get some smarty putting blog after blog on the same day, saying the same thing. like this Christmas basket person has done. At least then all the advertising blogs will be different. Perhaps too there could be a revue of the said site, its advertising, quality, accuracy and so on of the advert. a bit like they do with the see more hosting section on here.