The latest update to the original Angry Birds Seasons (v1.5.0) is now available for iOS devices and Android via the Android Marketplace and Amazon AppStore. More platforms will be coming online soon. This update includes a the summer themed episode named Summer Pignic (links to trailer).
You MUST BE CONNECTED TO THE INTERNET THE FIRST TIME YOU OPEN A LEVEL (only the first time) so that it can download the level file and check the date (this prevents early access).
AMslimfordy noticed that there might be a bug in the cumulative score counter that you see at the top of the screen when you pass a level. It seems to be pulling your score from Trick or Treat, not Summer Pignic. If you notice your score counter going up and up and up after you pass a level this is why. Just give it a minute and it will finish. I imagine Rovio will fix this bug.
From what we know this update includes:
30 new levels with ONE NEW LEVEL UNLOCKED EVERY DAY (remember Seasons Greedings?)!
5 new achievements
More Golden Eggs to be found (click for their locations and walkthroughs)
A “Big Basket” bonus level that is unlocked when you 3 star every level
Pig clouds (not really a feature, but I thought it was a cool touch)
The Golden Egg numbering discrepancy between the iPhone and iPad has been fixed.
Based on the trailer Summer Pignic should eventually be available for: iOS (iPhone, iPad, iTouch), Android, Mac, PC, Palm, Symbian, and Nook. If you missed the official game play trailer from Rovio check out this post.