How Much is Free Worth?

Chris Anderson bravely tries to put a figure on the value of the "free economy" - those businesses that use free as part of their model. What struck me is the extent to which the ecosystem that has grown up around GNU/Linux dominates everything else in this admittedly back-of-the-envelope calculation: $30 billion out of a rough $50 billion. Which confirms the extent to which open source continues to be the bellwether in this area - the first and still best example of how to make money by giving stuff away.