Citrix has recently released XenServer 6.5.
It’s now also available on all A1 Dedicated Servers. For existing users, you can request re-installation of your server with updated software. New users can select latest version on order page.
– runs on Xen 4.4
– Dom0 is now 64-bit (previously 32-bit)
– includes Open vSwitch 2.1.3
– improved performance with 3.10 kernel in Dom0
– support for more OSs
There’s more information in the official Release Notes, available here: http://support.citrix.com/article/CTX141498