GA must fulfill SkyTeams certain requirements in a given time frame, normally 1 - 1.5 years post joining announcement, if they don't satisfy the requirements, their entry will be deferred until they do or GA might be uninvited by SkyTeam. Only when GA and SkyTeam are satisfied, there will be a joining date given. So "by 2012" is only a guide, there is really no guaranteed date when they join.