I don't see a Dark Knight poster rip-off. There are a few resemblances. Poster also resembles that of Dredd, but maybe people didn't see that one (I know Ebert missed it; good movie btw). It's certainly nothing as blatant as ST 'ripping off' its own posters and slogans, something which I suspect they knew non-fans at the time wouldn't notice.
One dude on AintItCoolNews talkbacks commented that it's a poster about space, aliens and spaceships that does not show space, aliens or spaceships. Which I find interesting.
The similarities with the Dark Knight poster, I don't think they could have honestly expected people to miss it (or not try to accuse it of being 'ripped off' for that matter). Meaning it's now on them to really mean it, and to be confident that they are delivering a movie that isn't just a Dark Knight 'rip-off.' The disintegrating emblem speaks more to me than the synopsis: Starfleet is under attack from within. At its core, this has to mean something.
What is Starfleet? What is the Federation? I already know what Roddenberry thinks it is. I know what Berman thinks (Roddenberry thinks) it is. I know Bennett and Meyer didn't really care; it was the United States or something. I know DS9 had a few refreshingly original thoughts on the matter. And I know if you're talking to a drunken boy in a bar, you settle for saying it's an important peacekeeping armada and we need it. Maybe the target audience was that drunken boy. Star Trek? Why are you talking to me, man?
How do you dive into what Starfleet is to a 'movie' audience, which won't commit to the TV series on a weekly basis, in the space of two hours? Maybe you threaten to tear it down. The second movie of a franchise is usually its thematic core. The Dark Knight, The Empire Strikes Back, Superman II, Spider-Man 2, Terminator 2, The Godfather 2, X2, etc. It's the one where we find out what the Abrams team ultimately thinks Star Trek is. This is shaping up to be the movie naysayers accused them of not making last time.