Recently I was DM and the wizard decided to use "hammerfall step" to teleport a trap into a pit where it couldn't do anything. The trap was fixed to the floor so it could not be pushed, but could it be teleported?
I think that depends on the definition of what you consider a legal target for Hammerfall Step.
The power specifically states each enemy in blast. Source: Arcane Power pg. 116
Since I don't rule traps as enemies, I wouldn't allow him to teleport the trap at all. If it can't be picked up, it wouldn't be able to be teleported. Additionally, this would open the system up to massive abuse. If he can teleport a trap, then what's to stop him from teleporting the key to a blacksmith's shop? Or the spellbook he likes off a shelf? I mean the possibilities for abuse are endless if you permit him to use that power to move an object.