While messing around with minecarts in PE, i made this awesome secret entrance! Enjoy :)
Step 1: Minecarts!?
Note: You must have 0.8.0 version to use.
Follow the photos!
Step 2: Setting Up
Follow the arrangement of blocks in photo and push a cart down the rails and in between the half slabs.
Step 3: Destroy!
Destroy everything but the minecart and the two halfslabs supporting it.
Step 4: Camoflauge
You can use halfslabs to cover it. It IS possible with solid blocks. Just replace the halfslab on top in the first photo with a solid block.
Step 5: How to Use
Find the block with the minecart under it. Next, tap and hold over the block. And finally, jump to exit. You should now be in your secret room under the floor.