Why free is a very good price

Alex Pham in the LA Times blogs on Chris Anderson's new book. What's interesting is the numbers - Anderson is giving away a free version (non downloadable) on Scribd, and Pham writes 

"As of 1 p.m. today, less than 24 hours after it was released online, his book has been viewed for free by more than 22,800 readers on Scribd." Like wow! If that number can be extrapolated there could be a real business model there..