I picked up from Steve Rubel that Yahoo was preparing a "Technorati Killer". Steve is referencing another blog confirming that rumour.
While looking for more information about that, I came across that stunning post from Tristan Louis, a French expat to the US who is studying how Technorati ranks blogs. He evaluated a selection of blogs and looked at their number of links (now recognised as indicator of a blog popularity) in Google, Technorati and Yahoo. He then benchmarked the results against one another: Technorati v. Google , Technorati V. Yahoo and Google v. Yahoo (scroll down on that page).
The conclusions so far: Technorati is getting a fourth of links Google can locate. Yahoo does a better job at indexing the blogosphere than Google. "Smaller blogs seem to have a better chance of being recognised by Yahoo! than they do of being recognized by Google".
Tristan is looking at benchmarking all of that with MSN now...