On Mon, 05 Sep 2011 09:17:22 +0300, Itay wrote:
(...)
 
> 1) To remove the user from plugdev group.
>     (But how to avoid future new users from being added to that group?)
(...)
Mmm... you can edit the default settings for users creation ("/etc/
adduser.conf") and removing that concrete group.
Greetings,
-- 
Camaleón