What was the first app to do a staged rollout or invite-only launch?

It's commonplace these days for apps to do "staged rollouts" or stagger invites for new adopters.<p>This trend obviously grew from the concept of pre-launch email signups, and seems to have turned into more of a marketing gimmick than actual necessity. Smaller apps and startups have adopted the practice from big boys like Google to enhance their image.<p>To me, this is the digital equivalent of making you stand in line to get into a club - making it appear more crackin than it actually is.<p>My question is - what was the first app or service to do the whole "invite" thing?