Big warning though - today being what it is this might not prove to be the proper cover. This is supposedly the cover that shows up in the comic retailers pre-order book.
From what the covers shows it looks like the rumors about the Eldar Nightspinner are correct. We can also only assume that the Manticore on the cover will be one of the new Imperial Guard models that will be released.
Having just finished up my converted Manticore I am pretty excited about a non-Forgeworld kit being available - in plastic to boot! I will definitely be pikcing one of these up -more than one if it also makes a Deathstrike Launcher like is rumored.
I'll keep an eye on this and see if turns out to be an April fools joke and will update this post with any new info that I can find.