I was playing Minecraft Pocket Edition (the paid version), and noticed that in my crafting table, I could craft something called a 'Nether Reactor'. I could not find anything about it online (or maybe I didn't look close enough). So, my question is, did MOJANG create a new block while I wasn't looking, or is this Pocket Edition specific.
There is this question about reusing one, but it doesn't tell what it does. What does it do and how can I use it?