David Sifry has posted his latest State of the Blogosphere posting. Here is what he has to say about splogs:
There has been an increase in the overall noise level in the blogosphere, most notably in the number of spam and fake pings that are sent - what I call “spings”. These spam pings are fake or bogus notifications that a blog has been updated; in some cases, these spings can amount to a denial-of-service attack, and can sometimes account for as much as 60% of the total pings Technorati receives. However, we’ve built a sophisticated system that mitigates the spings, and helps to keep spam blogs out of our indexes. Beyond that, about 9% of new blogs are spam or machine generated, or are attempts to create link farms or click fraud. Technorati continues to take an ecosystem approach to solving this problem, working closely with other players like Amazon, AOL, Ask Jeeves, Drupal, Google, MSN, Six Apart, Tucows, Wordpress and Yahoo, and there will be another Web 2.0 Spam Squashing Summit this spring, building on the success of the previous two summits.
I suspect they are under counting the number of splogs out there. I have a couple of Technorati search feeds and see large amounts of splogs in the continually.