Pokerstars is claiming it's 50 billionth hand today. I just did the maths, and for Pokerstars to have had 50 billion hands (giving each hand a VERY generously short 20 seconds), Pokerstars would have had to have had an average of at least 3,787,925 tables at any given moment.

Given that just a couple of years ago they were celebrating their 20 millionth member (giving each table an average of 5 players, assuming that every single account belongs to a different person and every single player was on all the time), I find this ever so slightly improbable.