i have testet the new ms tool live writer and i must say its very handy, so is it possible that in future releases s9y will even work together with ms to provide serendipity support for the writer ?
Live Writer and Serendipity both support the Movable Type API. You can find some details on how to configure Live Writer here: http://www.s9y.org/210.html
Basically, you need to install the "Post via XML-RPC" plugin to your blog, and then configure Live Writer.
If you have any problems/feature requests, feel free to post them!