sudo, not su.

[elw at stderr.org]

> I'd like to draw devel@'s attention to trac bug 5537, which might land
> sometime soon:
>   http://dev.laptop.org/ticket/5537
> The upshot would be that, instead of logging in directly as root with
> no password, you would log in directly as *olpc* with no password, and
> then sudo to root (if you need root).  Please comment in the bug if
> you have strong objections and/or be prepared to try logging in as
> 'olpc' if 'root' seems to stop working in a new build.

+1

Yes, I think logging in directly as root is a misfeature that should go 
away.  Most of the other unix-derived platforms have been doing their best 
to kill it off or at least reduce its attractiveness... and being able to 
sudo is usually pretty trivial.

--elijah