Social Media Spending To Hit $50 Million This Year: Study

Hard to predict these things, but someone’s trying: The total marketing spend on social media is to grow at a CAGR of 106.1% from 2005 to 2010, reaching $757 million in 2010, according to a report from PQ Media.
Combined spending on blog, podcast and RSS advertising grew 198.4% to $20.4 million in 2005 and is expected to grow another 144.9% to $49.8 million this year. The study also says that podcast advertising is expected to become a larger market than blog ads by 2010.
Some other numbers for 2005: blog adv: $16.6 million; podcast adv: $3.1 million; RSS advertising: $650,000 (really?)
I would like to know the methodology and the universe they are looking at…numbers seem very low.