Text (DK+errata): You may play an additional land during your turn if that land is a basic Forest. ; Sacrifice ~this~: Add {G}{G} to your mana pool. [Oracle 2003/07/01]
You play the land as normal, but get to ignore the "one per turn" limit for a basic forest. [D'Angelo 1999/09/20]
You have to say when you put the land out that it is the one you get because of Gaea's Touch. [Duelist Magazine #6, Page 131] Thus, you cannot put out a Forest, play Gaea's Touch, then play another land claiming that the first one was under Gaea's Touch.
Can get a Snow-Covered Forest. [Duelist Magazine #6, Page 132]
Extended tournaments (see Rule 913) have banned this card since 1999/10/01.