Adventures in Ponyville sent these in, where they were posted on the MLP Arena. The Zoom ‘n Go toys found on Taobao have a pony with molded hair and moveable joints, an accessory and a little cart.
How exactly these work is unclear. They might be pull-back toys that have an internal gear that moves them forwards or they might only be push-along toys. They look to be about the same size as playful pony brushables.
They will most likely release at the same time as the rest of the Rainbow Power main line. Pictures of the Pinkie Pie toy under the page break.