DC's unveiled a big picture of the four page gatefold in the Free Comic Book Day issue (which I didn't get - need to speak to my comic book guy)
and Newsarama has a link to an absolutely massive version of it.
Not wanting to miss out on the speculation about Trinity War, I thought I'd have a quick look and see what we've got:
Deadman vs Black Adam - we've not yet seen Adam return though there's no doubt he will be back at some point. Magic and ghosts attacking each other, potential for Adam to be from a new version of Earth-S?
Vibe vs the Flash? Here's something a little out of nowhere - Vibe appears to be back. The much maligned character from Justice League Detroit is taking on the Flash. Different timelines, different worlds?
Wonder Woman vs Aquaman. Both appear to be the New 52 versions, though Aquaman looks a little different though that might be the colouring of his hair.
Element Woman vs Cyborg. We last saw Element Woman in last year's Flashpoint story although she then turned up in promotional material for the Justice League series. Another timeline/alternate world reference?
Superman vs Green Lantern. Excuse me truncating this fight but here we have the most obviously altered character in what appears to be John Stewart in a different costume. Again, though, I'm thinking alternate worlds.
Hawkman vs Green Arrow. And if any two were meant to go up against each other, it had to be this pair I suppose!
Atom vs Batman. As mentioned in the Newsarama article, the Atom here appears to be a woman which again smacks of alternate worlds - I'm thinking the old Earth-11 which had gender reversed heroes.
Something that strikes me is that with the possible exception of Black Adam, the entire battle is made up of heroes attacking heroes, and even Adam was on the side of the angels for a while in the old JSA title. The Green Lantern looks different enough to be a completely different character which makes me think that, after the successful launch of Earth 2 this week, we may be looking at a new Earth 3 which, at a push, could link up with the trinity aspect. Maybe the trinity going to war are the heroes of three earths?