The characters and universe, originally created in the mid ‘90s by Dwayne McDuffie, Denys Cowan, Michael Davis and Derek T. Dingle were owned by Milestone Media, a wholly separate business entity from DC Comics, but were published by DC through an agreement which saw the characters exist in their own separate universe. Milestone ceased publication of its comics in 1997, and ever since, fans have wondered when they would come back.
Dan Dido had this to say...
They’re coming back, and are coming right into the forefront, and right into the big storylines in the DC Universe. The great thing is, we have Dwayne McDuffie who is one of the owners and creators of the Milestone characters working for us and also of course, writing Justice League of America, so he’s going to finding ways to incorporate the characters into the storylines that are going to be unfolding within Justice League. We were also able to find a way with Dwayne to work other Milestone characters into other areas and series of the DCU.
we will be seeing this as if all our characters are meeting the Milestone characters for the first time. Even though we had the “Worlds Collide” crossover in the mid ‘90s, we will not be addressing that storyline. Instead, we will be meeting them for the first time within the DC Universe.
Also – we will be working on a couple of other levels with Dwayne on this. We will be collecting the old Milestone material, and reissuing that in trade paperback form over the course of next year, and also, we’ll be working with Dwayne to do a wrap-up for the original Milestone series for the way it was all presented. He had a concluding story that we want to work with him on, and that will be an out of DC continuity story, but completely within the original Milestone continuity. That way, the fans of Milestone from years back will be able to get that ending story that brings that original history and world to a close.
Sounds pretty interesting, it's been a while since i've read any Milestone stuff but it might be worth brushing up on the old stuff just to brush up with all of the characters...