01.) An imaginary award given to persons who state the obvious.
02.) Also used in a sarcastic sense to agree with someone, similar to "ok, if you say so". Usually used only when the person being "agreed" with is stating an extremely unpopular opinion.
03.) Can also be used in a genuine manner, similar to "thank you". (see example 3)
<guy_1> dude, macs are expensive
<guy_2> the world cup, it's yours
<guy_1> hitler was gay
<guy_2> no, hitler had the right idea
<guy_1> ... you win the world cup
<guy_1> anyone have last night's mozilla binary?
<guy_2> i do
<guy_1> world cup == yours