How Much Bandwidth is Required to Aggregate Blogs?

Kevin Burton writes "Technorati recently published that they're seeing 900k new posts per day. PubSub says they're seeing 1.8M. With all these posts per day how much raw bandwidth is required? Due to innefficiencies in RSS aggregation protocols a little math is required to understand this problem." And more importantly, with millions of posts, what percentage of them have any real value, and how do busy people find that .001%?