I don't even play more than 2-3 Wastelands in my Stax builds because everyone is running 30 fetches, 20 basics and 2 duals.
Steve cites the right reasons for playing it.
That's right on. I don't even play Wastelands in my Fish builds anymore because the extreme adaptation to Wasteland has weakened it so much. It's hard to justify playing a watered down mana denial strategy in a format that often makes 6 mana on the second turn.
On the other hand, I have been running Library of Alexandria in Fish for months now. It's a great card. Great v. control, aggro control, and occasionally amazing against Stax and other random things.
-B