Delivering continuous deployment of xen-api at cloud scale, John Garbutt, Rackspace

Currently xen-api is really only installed today as part of XenServer. It has traditional enterprise style releases, with controlled upgrades and hotfixes when required.
When deploying OpenStack Rackspace, with the help of the OpenStack community, have adopted an approach where any check-in could be deployed, and the system upgraded, from any other checkin from that last release, or earlier in the current release.
It would be interesting to see if xen-api could move towards a model. At a minimum having more regular check points where an upgrade would be possible.