Affects Version/s: Minecraft 14w18a
Fix Version/s: None
Environment:Java 7, Macbook Pro (Mavericks OS X) V10.9.2
You'll crash if you place a itemframe above a NON-sticky piston, with blocks under it to the void.
The world becomes "Corrupt" and you can not get back in.
I did this by...
Placing a piston, on a superflat world.
Ontop of that, placing a iron, one off to the west.
Placing a item frame on the iron block, so it is above the piston.