If one would only be allowed to distribute Linux, if
one did pay
Linus Thorwalds for every copy, then Linux would not only fail to
be "free" as in beer, it also would not be free as in "libre". The
distribution must be allowed without any charges, as soon as I have
the good.
I think that's a popular interpretation of the GPL, but in fact I
think you only have to distribute source code to those parties that
have received a binary. You can sell binaries for whatever you like -
Red Hat tm Enterprise AS Premium costs US $2499-$18000 for one year
of updates, depending on processor architecture:
http://www.redhat.com/apps/commerce/rhel/as/
Most of the commercial Linux distributors are using trademarks (eg Red
Hat tm), non-GPL essential components (eg SUSE's installer), or
lock-in to update services (Red Hat tm Enterprise) to frustrate
third-party commercial redistribution.
(All trademarks in this email are acknowledged to belong to their
respective owners).
Cheers
Daniel