Technorati's index seems to be rather forgetful: it does not find blog posts older than six months. Frankly, I don't know if it's a new "feature", or it's always been like this, and I'm just the last person to notice it.
Link authority has always been counted based on the revolving 6-month numbers, but I haven't found any reference in Technorati's FAQ that they only keep 6 months' worth of index. I've only done limited testing, but if indeed this is the case, then Technorati is toast. There's a lot of value in old posts, and the index that finds them in not Technorati, but Google.
http://feeds.feedburner.com/~r/zoli/~3/179580275/