Via Geoff Johns' blog:
I can talk about it.
This week, with LEGION OF THREE WORLDS #4, I can finally talk about August’s upcoming ADVENTURE COMICS #1/#504!!
The series will feature one of my favorite characters to write and a mainstay of my run on TEEN TITANS - SUPERBOY.
You can get a look at some amazing pages from issue #1 illustrated by Francis Manipul at the DCU Blog. Francis and I have been talking about Superboy since last San Diego Comic Con and it’s nice to finally see it come to light.
But that’s not all. It can’t be, right? I mean, it’s called ADVENTURE COMICS. It’s not called SUPERBOY. That’s because the series won’t just be featuring Superboy, it’ll be co-featuring the Legion of Super-Heroes fresh from the Crisis of the 31st Century in LEGION OF THREE WORLDS. More on the details of the book, and Superboy and the Legion, will be coming out in the following weeks, but I think it’s safe to reveal that STARMAN will be the Legionnaire taking front and center stage with our first issue.
Interesting that he references issue #504, which means that they're including "Adventure Comics Presents Dial H for Hero" and the digests in the numbering. We had that discussion here a few months ago. And don't forget that this is actually Adventure Comics v3.
The DCU Blog post shows the cover to Adventure Comics #1, with the center figure now revealed to be Superboy, but with the lower left figure still obscured. Based on the cape, it's likely to be Mon-El, but who knows.