So, I log on to one of my chars in Stormwind City last night (can't remember the time), but the place is in mayhem with a Horde attack and I get one shot (only level 25 see), Masses and masses of Horde rampant in the Trade District.
Well done indeed.
I rezzed in the Inn, and went upstairs to bed to sleep until it was over.
Fortunately, I had one char not in SWC and quested in Duskwood and did other stuff until the invasion was over.
Hopefully, the Alliance can respond in some way.