There are no pics as of yet, but Keldeo becomes the fifth legendary Pokémon to get an alternate form in BW2. THAT'S ENOUGH. Just like Thundurus and Landorus, there's absolutely no need for one. I know I'm repeating myself, but remember when having multiple forms was something special? Now half of the gen 5 legendaries have them. Sheesh.
Edit (June 10): Well, CoroCoro gave us a sneak peek at Keldeo's Resolution form, and... well, it's the laziest yet, with Keldeo only having a bigger mane and a longer horn. Boooooooo.