Coincidentally, I came across an article about code contributions. This article specifically mentions the contributions (or lack thereof) of CentOS and others.
"Then
there are the distros that base themselves off of other distros, like
Ubuntu and [Lance Davis'] CentOS. These distros have yet another layer
between them and the original developers. Patches rarely, if ever, flow
backwards into an upstream distro, and the developers are very unlikely
to push their changes into the upstream packages as they don't feel the
need or don't realize the issues involved as they rely on the upstream
distro so tightly," said Kroah-Hartman.
http://www.sdtimes.com/RED_HAT_TOPS_LIST_OF_CORPORATE_LINUX_CODE_CONTRIBUTORS/About_LINUX_and_OPENSOURCE_and_CANONICAL_and_REDHAT/32870
Kroah-Hartman is the maintainer of the USB kernel subsystem. His views are clearly more from a Linux kernel perspective, but they're interesting nonetheless. There were some surprising statistics in regards to the Canonical contribution - they make me wonder if perhaps something was missed. Perhaps the Canonical folks use Debian email addresses?
Jeffrey.
Red Hat gains something else of value from the cloners' existence: There is now a far larger base of machines running binaries compiled from the same sources that RH uses, so if a CentOS user finds a bug, and reports it to the CentOS folks, they can confirm that the bug does in fact exist, write it up and get information to upstream, which would include RH. RH isn't having to do any work to support these machines but gets these gamma testers to help them find bugs.