[Useless]

My understanding of the situaton is that in order to be penalized for duplicate content, page B would have to have many similarities to page A. Simply aggregating other peoples' posts and allowing them to mix with your own, on your unique site, shouldn't even bring you close to a penatly. With the popularity of RSS feeds being used on, and pulled from major mainstream sites, I get the sense that very few people who are "in the know" are worried about being penalized. Articles and blog posts have been republished across this mighty web for a considerable period now. If Google viewed the re-use of some content as duplicate, we would have known by now.

Also, blogs are not static - or at least they shouldn't be. Blog content is always updating and changing. You'd be hard pressed to convince me that the average blog would need to worry about the dupe penatly.