Blog clients that make use of the blogger.getUsersBlogs XML-RPC method get confused when talking with WordPress (specifically, WPMU). See http://joseph.randomnetworks.com/archives/2008/06/10/blog-id-in-wordpress-and-xml-rpc-blog-apis/ for details.
The wp.getUsersBlogs method is basically the same thing as the blogger.getUsersBlogs, with an additional field: xmlrpc. In the case of regular WP it just calls blogger.getUsersBlogs, since there's only one blog to report any way. For WPMU it will report the list of blogs the user has access to.
While here, I added the xmlrpc field to blogger.getUsersBlogs. If clients know to use that field then they should also know not to make assumptions about blog_id that don't hold true in WordPress.
