Hittade detta tips på webben, gällande problem med att posta bilder direkt till bloggen utan att använda ftp.
We’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 can’t upload images to recent versions of WordPress: when you try to publish, you get the standard “The following images cannot be published because the weblog does not support image publishing” 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.