Just as promised, Rovio, the maker of the oh-so-popular Angry Birds, released a separate game called Angry Birds Seasons today, which contains 45 Halloween levels, previously only available on iOS, as well as 25 Christmas levels.

I haven't spotted any new birds yet, and I doubt they've added any, but I'm sure a few hours later, when you all finish every level, you will let us know. Oops, I take that back - the snow levels are available one per day, starting today, all the way through December 25th (see the last screenshot to see what happens if you try to click on day 2).