Minecraft 1.7 is out now! This is the "piston update". Pistons have been added and require a few crafted items to build.
Cobblestone, Redstone dust, wooden planks and iron ingots must all be used to create the piston. Pistons can be used for moving other blocks. Interestingly enough, you can use a piston and a slimeball to make a "sticky piston" which as the name implies, makes the block it;s moving stick to it. I've already seen them used for advanced gates on fences and such. What do you use pistons for?