Hittade detta tips på webben, gällande problem med att posta bilder direkt till bloggen utan att använda ftp.
Weâ€™ve seen random problems with custom WordPress installations with WordPress server plugins installed. A good place to start is to disable your WordPress plugins and see if your problems go away.
Update 3/9/2006: Some users have been reporting that Writer canâ€™t upload images to recent versions of WordPress: when you try to publish, you get the standard â€œThe following images cannot be published because the weblog does not support image publishingâ€ error. This may be due to WordPress being unable to create/modify its <wordpress>/wp-content/uploads directory (if so, you will see an error to this effect even when trying to upload files through the WordPress web-based interface). To fix, make sure that the directory exists, and that it can be modified by the user account that WP uses.