ME and Ophelia

DOES GOOGLE NOT KNOW EVERYTHING -
Or are there a lot less number of blogs than estimated?

Perseus randomly surveyed 3,634 blogs on eight leading blog-hosting services to develop a model of blog populations. Based on this research, Perseus estimates that 4.12 million blogs have been created on these services: Blog-City, BlogSpot, Diaryland, LiveJournal, Pitas, TypePad, Weblogger and Xanga.

Recently, I visited Google's Web Directory where it states that the Google directory contains over 1.5 million URLs. But the Perseus survey estimates there are 4.12 million hosted blogs. Does Google not know everything, or are there a lot less blogs than estimated?
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TECHNORATI WEB SERVICES FOR BLOGGERS
Brand new quick service

Technorati launches a new service for bloggers.

Source courtesy of Joi Ito's Web