Please see my Gallery demo site, particularly these posts:
(three columns)
http://agallerydemo.wordpress.com/2012/12/16/media-update-multiple-galleries-and-single-images/
(two columns)
http://agallerydemo.wordpress.com/2012/07/28/gallery-as-an-index-page/
(one column)
http://agallerydemo.wordpress.com/2011/03/15/include-from-media-library-gallery/