The episode trailer of Angry Birds Seasons: Summer Pignic is released on YouTube. It's about smashing pigs after all.
The video doesn't reveal much apart from hinting "One bird, one mission: Save the eggs from the green pigs" (but you already knew that if you were a fan of the Angry Birds series).
From release notes on YouTube:
Get Ready for Angry Birds Seasons -- Summer Pignic! The pesky pigs never break for holidays, and it's up to you to save the Angry Birds' eggs!