I've never heard of this before (at least not called "pepper") - I think I've heard similar things called stuff like 'sidewide salt' and 'per-password salt'. "

I've never heard of this before (at least not called "pepper") - I think I've heard similar things called stuff like 'sidewide salt' and 'per-password salt'. "peppering" as described is conceptually similar to storing passwords as HMAC's under some key not stored in the database.