When I visited Memeorandum, Megit, Tailrank and Chuquet (and others) I simply saw the same news headlines being displayed over and over. They didn't keep my attention. Technorati is impressive, but largely the same: simply a news source.
I have found some really interesting blog posts that imply that the art of meme tracking has not yet truly been invented yet. (That's great news, because then we still have a chance of getting this right with our own software!)
This next link is a ripper! (The irony can be seen by first reading this post by Scoble)
The key thing here is that Scoble (and others) wanted to follow the hype of the day – memeorandum does an excellent job of tracking the hype, who's saying what and about whom. In this way there is an ever-present flow of energy as the blogosphere (the people) jump from one topic to the next.
My point is this: hype /= relevance. You can remain hyped, or you can do some real work, do something useful or learn something new. But hype is just that – opinion followed by the energetic opinion of a bunch of people. It's no indicator of the usefulness, originality or value of the post.
Most of the best posts on any topic are still found through a search engine, because they are old and have long since fallen off memeorandum or technorati.
BTW: You'll notice that I happily post old blog posts – but that's because I'm not all that interested in New! as much as I am interested in Relevant! (As I find great posts on the topic of meme's, semantic web, web 2.0 and more. I'll put them in here. Enjoy!)