10/4/2004: You have to say when you put the land out that it is the one you get because of Gaea's Touch. Thus, you can't put out a Forest, play Gaea's Touch, then play another land claiming that the first one was under Gaea's Touch.
10/4/2004: You play the land as normal, but get to ignore the "one per turn" limit for a basic forest.
10/15/2006: Applies to a Snow-Covered Forest, since it has the supertype Basic.