Basicly its the convention for computer animators, animators, graphic desginers artists etc only.

Most of the major companys are there and will hire people on the spot. They also have seminars you can go to that help with the art field your in.

Also if your a member of siggraph they have meetings once a month where yyou can get job listings etc.

The convention it's self is a lot of fun. A friend of mine draged me to it several years ago.

http://www.siggraph.org/
More information can be found there about the orginization

The actual convention information is here
http://www.siggraph.org/s2005/

very fun though because major companys are there