I'd be interested to see the family tree of these new Linux flavors that favor Python over Perl.
Most Linux flavors start as a branch from existing ones. They only change what is most important to differentiate themselves. If they're derived from Mandrake/Mandriva, they likely use Perl very centrally. If they are derived from something that uses Python for installation and package management, they'll likely use that too. This says, I think, more about the success of a main branch of Linux distributions than about Perl or Python specifically. Only if someone rips one out in favor of the other is it very important to language popularity.
I've yet to see a distribution that doesn't offer perl. Some include it as part of their developers packages. Some offer it as its own item. Some don't allow you to deselect it, because it's considered vital to the system. Python is also being offered on lots of distros, but I'm not as certain about where it might not be since it's not on my must-have checklist for trying a distro.