I use the spreadplayers command in combination with the spawnpoint command in my map to minimalize spawn camping.

The player should be teleported to a random point in the map from wich he can play without getting killed.

The player is teleported to the point, but invisible, untouchable
and shown as the command block would be his point he teleported.
As long he hasn't taken damage or entered the game once again no other player will be able to see or touch him.

To Reproduce do as following:
1. set the players spawn above a command block using spawnpoint
2. put a pressureplate on top
3. set the command to "spreadplayers [x] [z] *(min1) *(min1) false @a[r=2] "
4. kill a player and let him teleport to the point
5. look at the command block (he should be there)
6. go to the point he teleported to (he shouldn't be there)
7. let him take fall damage (or something else) and he sould reappear