Yet another blogger exaggerates the number of people who read political blogs. This time the claim is that 57 top liberal blogs have as large an audience as CNN and MSNBC combined. The implication is that advertisers should pay as much for ads on liberals blogs as they now pay for ads on cable television.

The most reliable estimate I’ve seen says Daily Kos, by far the most highly-trafficked political blog, had 212,000 unique readers in April. CNN and MSNBC often get more than 1,000,000 viewers in one evening.

No one disputes that blogs are growing fast in both traffic and influence, but many of the claims about huge blog readership (often put forth by bloggers angling for advertising dollars) cannot be taken seriously.