As of Friday, EPEL 7 is open for development as announced by Dennis Gilmore on devel-announce. EPEL 7, like earlier versions of EPEL, are for providing extra packages -- commonly from the Fedora world -- in a yum repository for RHEL users for packages not found and maintained by Red Hat in the official RHEL archive.
EPEL 7 is targeting RHEL 7 public betas that began surfacing last month. Red Hat Enterprise Linux 7 is already looking and running great and now there's a wealth of extra packages available for easy installation.
The current list of EPEL 7 development packages can be found via this Wiki page and the FAQ page provides additional information for early adopters of RHEL 7. Aside from the official RHEL 7, there's already work on the CentOS 7 version especially now that Red Hat and CentOS have formally hooked up.