Under this partnership, Red Hat and CentOS will be collaborating. Under Red Hat's umbrella, CentOS will serve as "community integration beyond the operating system" where as Fedora will continue to be about "operating system innovation across the stack" and RHEL of course is what Red Hat will continue to push for commercial customers.
For the past ten years CentOS has been the leading community rebuild of Red Hat Enterprise Linux source packages and now it's getting a bigger role under Red Hat.
The Red Hat press release notes, "Red Hat will contribute its resources and expertise in building thriving open source communities to the new CentOS Project to help establish more open project governance and a roadmap, broaden opportunities for participation, open pathways for contribution, and provide new ways for CentOS users and contributors to bring the power of open source innovation to all areas of the software stack. With Red Hat's contributions and investment, the CentOS Project will be able to expand and accelerate, serving the needs of community members who require different or faster-moving components layered on top of CentOS, expanding on existing efforts to collaborate with open source projects such as OpenStack, RDO, Gluster, OpenShift Origin, and oVirt."
CentOS.org has also already been overhauled and notes Red Hat's new partner.