_I_ think RH silently went from time based to feature based.
I guess they want a kernel with a fairly ready BtrFS and some other stuff (KVM, maybe RT and also higher up the stack.)
If think about it it makes sense. Selling an OS with Ext4 in 2012? I don't think so. KVM has to replace the current Xen etc.
IMHO going feature based and even longer release cycles makes sense for an enterprise distro with a subscription business model. There is always Fedora (if you are into BDSM that is .. JK)
And I think the lifetime of RH5 will be extended even more.