I have Minecraft Pocket Edition and I have collected a lot of redstone dust. For some reason, I couldn't use it for things such as iron doors. Why?
Redstone circuits haven't been added to pocket edition yet. Currently, the only uses of redstone are certain crafting recipes such as powered rails.
Pe 0.8.1 or 0.8.0 has redstone dust as a collectable item but is only use for compasses clocks and powered rails
It's really bad that redstone circuits haven't been added yet, so all you can do is make compasses, clocks and rails. Let's hope for those iron doors soon! :)