After a hard searh, most articles tells us how to modify xmlrpc.php, indeed, it is the solution to wordpress before offical bug solution came out. Unluckly, it does not work to me, who use wordpress 2.6
WordPress API for Zoundry Raven, Flickr, ScribeFire
Can not use WordPress API, those Zoundry Raven, Flickr, ScribeFire can not work. When I try http://www.adamghost.com/xmlrpc.php , it shows that: XML-RPC server accepts POST requests only.
login to your dashboard, goto settings/writing/remote publishing
tick the box
XML-RPC Enable the WordPress, Movable Type, MetaWeblog and Blogger XML-RPC publishing protocols.”
then test – this worked for me!!