Jeff Jarvis had it right. There is no end of inventory. But that doesn't stop The Wall Street Journal from looking like it's a hop, step and a jump behind the conversation regarding the long tail.
It's one of my biggest frustrations about the online media business - Too many media planners believe that the "Big Three" are where the only action is because they're the biggest, traffic-wise. Either they believe that deals with smaller sites aren't worth the trouble or they fail to realize that aggregating huge chunks of their target audiences in one place is no longer a prerequisite of doing business. Or they like seeing their ad on the home page of Yahoo just like they like seeing their commercial in the Super Bowl.