The short answer is this: you don't have to do anything! It will Just Work.
The first thing to understand is that on the day of a Fedora release, Rawhide and the actual Release are *exactly the same*. Rawhide, at this point, will have been frozen for about a week, and will not yet have opened up for contributions to the next release. And that is pretty much where we are right now. Rawhide *is* Fedora 8, and that will still hold true on the release day.
Everything else related to this question has to do with the fedora-release package on your machine.
The fedora-release package contains the release name, RPM gpg keys, some kickstart files, and most importantly, the yum repo files that tell your machine how to go about updating itself.
Let's take a look at what's on my laptop right now.
spevack@localhost ~ % rpm -q fedora-release fedora-release-8-3
This package ships 4 yum repository files:
spevack@localhost ~ % rpm -ql fedora-release | grep yum /etc/yum.repos.d /etc/yum.repos.d/fedora-development.repo /etc/yum.repos.d/fedora-updates-testing.repo /etc/yum.repos.d/fedora-updates.repo /etc/yum.repos.d/fedora.repo
Let's take a quick look at what repositories are enabled, or disabled:
spevack@localhost /etc/yum.repos.d % grep enabled=1 * fedora.repo:enabled=1 fedora-updates.repo:enabled=1
This shows us that there is a repository enabled in the fedora.repo file and in the fedora-updates.repo file. If I look in those files, in both cases that is the Fedora 8 repository that will live at /pub/fedora/linux/releases/8/ in our mirror directory structure.
But if you have been using Rawhide since Fedora 8 Test 1 or something like that, you have been used to having the fedora-developent.repo file be enabled, and the main fedora and fedora-updates files disabled (because otherwise you'd be getting the Fedora 7 packages, and not the Fedora 8 development ones).
As the Fedora 8 Release Candidates have come out in the past few days, Jesse made the change to fedora-release to have it point to the /releases/8/ directory instead of /development/ because that is how it has to look for the final release of Fedora 8.
That /releases/8/ directory isn't active yet, because Fedora 8 hasn't been released yet. But our mirrors currently have a redirect that points over to Rawhide. On Thursday, it is a trivial operation for Jesse to take that redirect away. Then the Fedora 8 directory is active -- people can install, we can push updates, etc. Separately, Rawhide can then be opened back up for Fedora 9 development, and a new fedora-release package that configures yum to look back at Rawhide will be placed in it. People who want Rawhide can install that package or tweak their yum repository files and be off and running.
What's the point of all of this?
It makes the upgrade path as hands-off as possible. Chances are that if you installed a Test release of Fedora or a Release Candidate, you want the final version of the release when it is available -- you don't want to stick on Rawhide.
By altering the default settings in fedora-release at the right time, and also by using redirects, the Release Engineering team can achieve this affect without requiring the user to change anything.
So if you have installed one of the Test versions of Fedora, you are already all set up the way you need to be. Your machine will "become" Fedora 8 at the right time.
The folks who want to *always* run Rawhide are the ones that occasionally have to tweak something manually, but that's ok with us.