According to the "blogdex", the current most popular link on blogger blogs is First Evidence Of Life Coming From Space Reported.
Blogdex is "a system built to harness the power of personal news, amalgamating and organizing personal news content into one navigable source, moving democratic media to the masses." Basically, what they're doing (and have been, for nearly a week) is indexing several thousand blogs, extracting the links, and making a daily top ten list of them.
What we've learned today is that bloggers, as a community, are very interested in space-born bacteria. As news of blogdex travels through the blogging community, however, I'm predicting many links to blogdex itself (I just contributed one). What will happen when the number one link is to itself? Will it create a feedback loop that will cause it to self-destruct?
Here's an article about blogdex from Wired: Tracking Bloggers With Blogdex.