Mr. Greg Moore is right. "Good job", "you did good", "great work!", "well done", but sometimes, it is meant as sarcasm. It can also mean someone has done something foolish.

"You have just successfully made the most sales out of all our sales staff this month, way to go!" So the meaning of "way to go" is something similar to "well done", "good work" etc. It can also be used in an ironic sense, so be careful!

"Way to go" is used to congratulate, approve or encourage someone. As for its possible sarcastic use, well that applies to any expression. One could say "Brilliant" or "Perfect" or "Super" in a sarcastic way. But it's the intention (thus the tone of the voice etc.) not the word in itself to create a sarcastic effect.