themes are definitely up.
http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.0/themes/base/jquery-ui.css
this will get you the base theme. just replace base with any of the other theme names.so for vader:
http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.0/themes/vader/jquery-ui.css
basically: http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.0/themes/#THEMENAME#/jquery-ui.css