The Portal Gun Mod adds Portal 2 themed content to Minecraft. The highlighted feature is the Portal Gun which allows the player to place two portals and teleport instantly between them.
This mod was originally designed for use in adventure maps. As of December 26th, 2012, the Portal Gun Mod has been re-written to be balanced for use in survival Minecraft. Find more information about the re-write here.
There is an Easter Egg in the mod where if you shoot a portal at the moon and then shoot another portal anywhere else, it will create a vacuum that will suck in any blocks and players nearby. A player in survival mode will die similar to how a player would die in the void. Blocks and items sucked into the portal are lost, including items in a player's inventory. In creative mode, this portal teleports the player to y = 400m.