In addition, if you have rewrite rules for using wp-admin-ssl, you’ll have to modify them so that wp-content/plugins/wp-admin.php is accessible via https.

Finally, there is a thread on the wp-hackers mailing list about the idea of hiding /wp-content files. Specifically, Otto has several good reasons why hiding wp-contents makes no difference, since it hackers won’t scan for a plugins, they scan for vulnerabilities.

Except for inactive plugins, it doesn’t matter if someone can scan for a plugin.

Ciao!