Blogpulse tracks how much the blogosphere mentions a topic or brand. The unit of measure is percent of blogs that mention the keywords or an url. Nielsen BuzzMetric's blogpulse is slightly biased toward English language blogs although many blogs in other languages are represented.

In October 2004, Skype was mentioned in .015 to .020 percent of blogs.

In March 2005, Skype buzz was in the .045 range, doubling in six months.

Now Skype is in the .07 to .08 range, doubled in 18 months, with frequent spikes over .09 percent.

The chart above shows Skype's modest growth over the last six months. The bottom curve is "VoIP". When I first started looking at both of them, they overlapped. They used VoIP to explain Skype. Now they are mostly separate; Skype has its own identity independent of VoIP.

Just for comparison: Paris Hilton (.075), Harry Potter (.2), iPod (.5), election (.65), Iraq (.7) and sex (1.4%). From a marketing perspective, the new blogging service Vox is stable at .1 after launching its preview in August; Coke (.225, including all uses of the term) and Pepsi (.1).