Yes, it will air this fall with thirteen episodes.
Season 2, episode 25 (A Canterlot Wedding Part 1) came out on 4/21/2012.
At season 3 the last episode is 13. There will also be season 4 with 26 episodes.
The sonic rainboom appears in three episodes so far. The first is the aptly named Sonic Rainboom (season 1, episode 16), the second time is in The Cutie Mark Chronicles (season 1, episode 23) and the final time is in A Canterlot Wedding Part 2 (season 2, episode 26).
In the spring of 2015
November 23,2013
Well, S3 of mlp is over now. It's first episode aired on Nov. 10th, 2012, and ended on Feb. 16, 2013
we dont know yet but hasbro have confirmed season 5
November 10, 2012
November 10, 2012
it already came out, it is now on netflix
Well derpy was in the very first episode. I assume her biggest appearance though, would be when she has a speaking roll, which is in season 2, episode 14- The Last Round Up. She talks to Rainbow Dash.
There are 26 total episodes in the fourth season of My Little Pony: Friendship Is Magic.