XML-RPC changes from 1.5 to 1.5.1.3

I wrote the WordPressDash widget, and the WordPress version 1.5.1.3 release does not allow WordPressDash to successfully post to the blog. Has the specifications for posting via XML-RPC changed since 1.5? I receive a 404 error when trying to post (and I know its not a url problem, because I use the same url to get blog info from xml-rpc).