Yes, you heard that right. Apparently, if you've downloaded the free version but never bought anything, you're not a free-to-play Team Fortress 2 customer.
And if you have every bought anything for Team Fortress 2, you're a "premium" customer, which means a bigger backpack, better items, and all blueprints. It also means a "proof of purchase" hat.
More details are at the official Team Fortress site.
