Hello,
A couple of TODO items/suggestions:
1) Xen 4.2.4 was just released: http://lists.xen.org/archives/html/xen-devel/2014-02/msg01624.html
I think we should first update Xen4Centos6 rpms to Xen 4.2.4 to have a "known good" release from the stable branch currently in use in Xen4Centos6.
2) After that, we should start packaging/testing Xen 4.3.2: http://lists.xen.org/archives/html/xen-devel/2014-02/msg01622.html
Xen 4.3 brings much improved XL toolstack in addition to a lot of other changes/fixes.
3) After updating to Xen 4.3.2 rpms start troubleshooting/debugging the libvirt libxl driver and get it working with Xen4Centos6 system..
How does that sound like? :)
-- Pasi