When I read the wikipedia articles about RHEV and oVirt, I can't really figure out why Red Hat have both projects, as they seam to solve the same problem?
http://en.wikipedia.org/wiki/RHEV
http://en.wikipedia.org/wiki/OVirt
oVirt will be included in Fedora 17, so clearly they have invested a lot in both projects.
Is one of them a short term solution, or do they solve different problems/tasks?
Update
Based on this link, oVirt is only a manangement interface build up from common open source packages.
So I would speculate that the management part i RHEV will be replaced with oVirt at some point.