Thinking about it, Blizz do need to put in something to liven up the times between major patches.
A good visit from a wandering World Boss where people have to cooperate to take it down, or even just drive it away, would be a good idea. Have some dragon rock up to the front gate of SW and see how many people swarm out to drive it away.
As an incentive to get people to fight, have the NPCs hide and vendors in the city all close up shop and hide while the dragon is outside.
Add in an achievement for defending the city as a bonus. As a weekly event it could be fun.
And to make it a bit fairer for newbies and low level toons, toss in support roles for them to bring aid/repair material from the castle to the front gate to repair the damage made by the boss's attack or to boost fighting defenders.