TV Guide (This stuff still exists?) released a few of the upcoming episodes as well as summaries for each. There may be a few spoilers, you have been warned!
Also an Anonymous brony on /co/ is posting episode summaries up to the very end of season 1, with all sorts of things that would excite any FiM fan. I'm still waiting on the legitimacy of these, but for now, here are the next 4 CONFIRMED episodes. I will add the others in another post if they are actually real.
Episode 13: Fall Weather Friends
Airs: January 28, 2011
Synopsis: The ponies' competitive spirit takes over when they compete in the annual Running of the Leaves.
(Backwards seasons in Ponyville? They really are insane)
Episode 14: Suited for Success
Airs: February 4, 2011
Synopsis: Rarity becomes overwhelmed by details as she makes party dresses for her friends.
(Incoming awesome Rarity OCD episode!)
Episode 15: Feeling Pinkie Keen
Airs: February 11, 2011
Synopsis: Twilight Sparkle tries to understand Pinkie Pie's ability to predict the future.
Episode 16: Sonic Rainboom
Airs: February 18, 2011
Synopsis: Rarity disrupts a race while enjoying her new wings (courtesy of Twilight's magic) and watching Rainbow Dash compete
(RARITY OVERLOAD THIS MONTH HOLY SHIT)
The rest are all unconfirmed and probably fake, but if they are true, we can expect to see what appears to be an awesome Luna/Celestia story arc in the future.*edit* the person posting the descriptions admitted to them being fake. They sounded so amazing too... Sad rarity is sad.