Note: Final update can be found here. The gates are now open.
Recent days have seen a flood of level 1 alts on Medivh as players from other servers make the pilgrimage to Silithus in order to watch Ahn'Qiraj finally open. Additionally, the wait queue of this previously modestly-populated server has multiplied to over 500 and new guilds going by such names as "OPEN TEH GATE", "Aq Opens" and "Get In Queue Please" have swelled in their ranks.
Short of throwing down a blanket fix like a level limit on the entire zone of Silithus, which would likely disadvantage the lower levels players of Medivh that actually play on the server and contributed in some part to the war effort, Blizzard appears to have their work cut out for them if they wish to act upon the impending congestion. My guess? They'll sit on their hands, scrunch their eyes up tight, and hope for the best.
Gates opening or server booming, this could be something worth watching. If only the players videoing the event weren't going to stall and crash every 5 seconds...