Well I suppose it really depends, is it also the last date? ha, im playing.
If you are going to date someone, whats the rush? Why not take the time to get to know them -- who they are, what they are about, what they stand for, and etc. -- before you lay down with them.
If you're really trying to build with someone, a foundation based on the physical connection probably won't sustain like one based on mental connection. Besides, waiting on sex just adds to how much you actually value the simple company of that person.
If you're just looking for the physical (as long as both parties are aware of intent)..well, that's cool too. Just be cautious of the consequences of promiscuity.
Another great question from my Formspring.