Finally I did it. On downloads page, for members, I’m publishing those days the Newsletter Extensions in a WordPress plugin format. That means an extension can be installed as a regular plugin just uploading it directly from the blog plugin management panel.
No more FTP or folder to create.
The really interesting feature is the one click update. Being plugins, the extensions now can check if there are new versions available and offer the opportunity to update them self as done with other installed plugins, directly from the plugin list panel or from the WordPress update panel.
Actually this is possible since www.satollo.net can (partially) simulate a plugin repository.
The update is possible only if a license key is set on Newsletter main configuration panel. The lice key for members is available under the downloads page.