WAR announces 750,000 registered players

Mythic has a press release announcing 750,000 "registered players". Interesting term. I'd guess a "registered player" is more than a "copy sold", but less than a "subscriber", what do you think? In any case Mythic is also increasing their marketing effort, so there is a good chance that they'll reach the predicted 1 million players before Wrath of the Lich King causes a decrease in subscriptions again.