While we were busy talking about the Virtualization market in #centos the other day , someone didn't know that Citrix was now offering their XenServer enterprise for free (as in beer, not speech). I guess that it's a kind of answer to the fact that Vmware offers ESXi also for free (since late july 2008). The console app is almost an exact copy of the screen you get with ESXi (but i don't know who copied the other though). I don't want to compare both products or features but because I was already busy with CentOS 5.3 QA tests I thought that it was a good time to download/test it .. Unfortunately their Xencenter management application is still a MS-only application that depends on .Net 2.0 (like VI client for Vmware, even if VMware announced recently a that a VI client for linux would probably be released and that they have now a demo of VirtualCenter Linux version running on CentOS ..)
And guess what Citrix is (still) using for the dom0 ? CentOS ! okay not a 'real' CentOS anymore because some packages (including the kernel of course but still based on 2.6.18-92.1.10.el5) were replaced but most of the packages still come from CentOS (they were not even rebuilt and CentOS yum repositories are still in /etc/yum.repos.d/) .. That reminds me that someone else confirmed me that Oracle VM itself was based on Unbreakable (and so on CentOS/RHEL).