"We pushed out a change that will prompt some users to solve a ‘CAPTCHA’ if our spam classifier identifies the blog as spammy," wrote Google's Blogger Product Manager Jason Goldman on Blogger Buzz. "So far, we have observed a slight decrease in the amount of spam being created."
The CAPTCHA (an acronym for "completely automated public Turing test to tell computers and humans apart") test is a method by which automated programs that post or create blogs can be foiled. Typically the user is asked to type in a sequence of letters from a line that people can read but computers can't decipher.
In the last year, Google’s Blogger hosting service has become infested with “splogs,” fake blogs aimed at tricking search engines to artificially increase page ranks of certain websites while also loading up surfers’ computers with adware and spam-generating Trojans.
Splogs have spread at an astronomical rate thanks to automation software and tools offered by blogspot that allow sploggers to automatically populate the bogus blogs with keyword-optimized posts and Google AdSense advertisements.
The posts often feature the names of popular search terms and prominent bloggers such as Arianna Huffington in order to boost their visibility in searches at RSS aggregators like Feedster, PubSub and Bloglines.
Blog tracking site Technorati estimates that nearly 40,000 splogs have been created during the past week alone. FightSplog, a site that exists solely to monitor Blogger activity, says one splogger is responsible for creating more than 2,700 porn-related splogs.