[Plugin: WP Smart Sort] Broken with 3.1?

Ever since 3.1 my links I used to sort by custom field value have been broken. The following URL used to work up until 3.1. I wonder if this plugin is now broke?

http://waytooindie.com/reviews/category/movies/sort/_Rating-pm-asc/

Even a more generic sort (link below) that just uses an orderby=posts of a certain category now does not work.
http://waytooindie.com/reviews/category/movies/?orderby=posts

Any help would be great.

http://wordpress.org/extend/plugins/wp-smart-sort/