The issue is pretty well explained here: http://itpixie.com/2012/10/hide-your-wordpress-login-from-author-archive/#.UxSwJtyFbwK
There should be at least an option for that (say, a yes/no checkbox and a frontend name field) in the user's settings page. By the way, is it possible to make the username COMPLETELY invisible (even in the page's source code)? Even if not, we can at least make it not-so-obvious.