Accourding to this http://www.mmo-champion.com/content/...-Music-TCG-Art
We will be getting an item level 600 back for our troubles in helping Wrathion out.
As far as I know the current highest item level is 541 and would proberbly be a bit more for Ra-den drops.
But isn't the jump from 541 to 600 at bit high ? - It's not a new expansion - just a patch.