Some ponies seem to view episode titles and synopses as spoilers, so have a little copypasta from my own blog, Ponyleaks, after the break.
Air date: January 21, 2012, 15:00 UTC (10 a.m. EST) (time not confirmed)
Synopsis: “Applejack disappears and the friends set out on a journey to find her.” (Zap2it)
So this is our mysterious The Last Roundup. Neat.
Also, first again! Yay!