Xbox Wire stated:
Pistons have been a top-requested feature from the Minecraft community for a while, and we are excited to bring both standard and sticky pistons to players soon, which will enable you to build even more complex buildings and contraptions within the Pocket and Windows 10 versions of Minecraft, such as draw bridges and trap doors, to name a few.
Mojang has posted a change log of what will be included in the update. Among the new additions will be observer blocks, which will detect changes in neighboring blocks. There will also be pig riding, husk zombies in the desert and more.