That's a full million customers paying an extra $49 on top of the purchase of the game. Activision has to be psyched.
When the folks at Activision said that they weren't ready for the popularity of Call of Duty Elite, it seemed a little ridiculous. After all, the 'Modern Warfare' series is one of the biggest around, so high signup numbers should have been expected. Activision definitely couldn't have anticipated this much desire.
The free Call of Duty Elite service had four million signups in the first month. That's a good chunk of the people that own the game - half or more - but it's not shocking that people would sign up for something free. The Elite Premium service had a million gamers sign up for it. That's a million gamers at $49 a pop, paying for everything offered in the Premium program. That's on top of the $59 the game cost.
Game makers have long been looking for the thing that will help combat used game sales and it's clear that Activision is on to something here. Even if a player buys 'Modern Warfare 3' used from GameStop, they'll be paying their $49 straight to Activision if they want the Elite experience.
Based on the success of Call of Duty Elite Premium, you can expect to see this sort of thing showing up in other games as well.