Rail

Acts as a route for minecarts. Place a minecart on a laid track and push the cart along. The track forms corners where two perpendicular tracks meet. If there is a one-block height difference between two sections of track, the lower section will turn into a ramp. NOTE: This only works if there is room behind the ramp, i.e. having the ramp go down into a wall will cause the ramp to not form. Tracks can be formed into a Rollercoaster as well.

Caution: It appears that when tracks come into contact with water, they disappear in the same fashion as torches. Whether this is a bug or not is unknown.

This is also true for trees that grow over the area of a track; so be careful when laying them down.

Following the third secret update, it appears that the track turns can be controlled with a lever, causing them to change the turn direction.