"...we’ve been humbled by your enthusiasm -- and we sincerely regret that your crusade to bring down the Lord of Terror was thwarted not by mobs of demons, but by mortal infrastructure. As many of you are aware, technical issues occurring within hours after the game's launch led to players experiencing error messages and difficulty logging in. These issues cropped up again last night for the Americas and Europe servers. Despite very aggressive projections, our preparations for the launch of the game did not go far enough."
The community manger "Bashiok" goes on to say they have made adjustments where they can and are continuing to monitor the situation. Due to the technical difficulties Blizzard has also decided to delay the launch of the Real Money Auction House.