Sony's $65 million purchase of video-sharing site Grouper tops the blogs this morning. Most are caught up in the arcane nuances of Web traffic measurement. Why? Now that the Grouper deal has given online video a market valuation -- in dollars per viewer, mostly -- Grouper's larger rivals like YouTube have, at least in theory, price tags on their heads.

TechCrunch crunches the numbers, noting that ComScore says Grouper had 542,000 unique visitors in July, which would imply a value per viewer of $70. The implication? All caveats aside, Marshall Kirkpatrick writes, "... the $65 million valuation on Grouper suggests a YouTube valuation of around $2 billion." Astounding: YouTube's co-founders Chad Hurley and Steve Chen have seen their imputed valuation jump from $1 billion to $2 billion in less than a month.

Rafat Ali at PaidContent.org casts a more jaundiced eye on the news, however, pointing out that "the valuation is not really based on traffic." According to Ali, Sony is paying for "a solid management and technical team," as well as an online video-editing tool called "Groovie." Groovy.

And, lest you thought this market wasn't entertaining enough, Ali thinks there's more action to come: "This probably signifies the start of a shakeup in the video-sharing space," he writes. No doubt.

Is YouTube worth $2 billion? Tell us what you think by leaving a comment below.