The old thread for this seems to have blown up. That's fine since the title was incorrect anyway. It's "Genisys" not "Genesis" as we thought early on.
Teaser for the teaser: http://youtu.be/t_77GeNEzFQ
Directed by Alan Taylor.
It's sort of a reboot, but using the new Star Trek model, they're doing some time travel frippery to keep the "old" Terminator timeline valid while going to a new one.
If you're interested, tons of official plot spoilers here: http://popwatch.ew.com/2014/10/29/this-weeks-cover-first-look-at-terminator-genisys/