Redhat announced that they are going to release RHEL7 by second half of 2013 on the occasion of their 10th anniversary of RHEL1 release some 10 years back. Jim Totten,
vice president and general manager at Red Hat’s Platform business unit announced this in a webcast. There will be 2000 packages upgraded in this release and more improvements to support many hardware, security, Filesystems and performance.

Redhat releases their flagship distro for every 3 years and patches for every 6 months. Here is a quick release dates of all the Versions of RHEL taken from Wikipedia.org

Please free to share your knowledge on this.