One of the most interesting things about the real-time media marketplace is the way it is redefining how we think about time. Unlike other so-called real-time marketplaces, like Wall Street's financial markets, there are no "opens" or "closes" -- media inventory is constantly traded on Madison Avenue's ad exchanges, 24/7, and increasingly, in every time zone. I've written about that first point a number of times, but the second point -- the globalized nature of real-time media markets, and its implications -- is just starting to hit me.