I'm pretty certain that WarriorSmurf 666 means the "Statement of Intent/Purpose" in most art school applications.
I also desperately would like to know if there are any good examples available and how much of a priority they take in an art school's judgment of one's application. Are they just like the essays required in an application for a generic university?
Well, I typed "how to write an artist statement" into google and it came back with lots of helpful links to suggestions and examples.
I would think an art school would look at an artist's statement to discover
--what kind of a personality do you have?
--do you seem to have some kind of direction, passion, or goals with your art?
--can you talk coherently about yourself and your art?
--are you serious about studying art or are you just choosing it because you have nothing better to do?
I would think (and this is just my opinion) that an art school would consider the portfolio first and the artist's statement second. If they like your art, they will then look to the artist's statement to get a sense of your personality and see if you are the kind of person who would fit well at their school.