I think this is supposed to be the Shockpoint (/Dark Cybertron/Purple Reign) thing.
Or at least, Shockpoint is the name that is wafted around when 'big event' is also mentioned.
I'm trying to avoid all the hype, especially the one coming from comic publishers, just to be on the safe side.
But I have to admit I'm a little excited.
I'm hoping for a complete retcon, actually. Shockwave goes back in time, and makes sure the war does not end. BAM.