G4TV.com has the trailer, which features Mandalorians and the planet Mandalore.
Thanks to BFFC's therealmccoy for the tip!
Updated 7/26 11:45pm: The Hollywood Reporter notes "As reported in the panel session, the series is getting darker and more violent in season two. ... [T]he supervising director told fans Boba Fett will be in this season, though I'm not sure if the helmeted Mandalorian guy in the trailer is him or not ... just texted the LucasFilm PR rep, and he replied with "No comment!" -- hmm..."