Dobrze posłuchać informacji z pierwszej ręki.
BTW sporo zmian w 6.1, jak na tak oszczędny skok numeracyjny.

Product Naming / numbering scheme

For a variety of reasons, we’re no longer going to use the “Service Pack” and “Feature Pack” nomenclature for XenServer, and will go strictly with a x.y.z numbering scheme. So 6.0 is actually “6.0.0.” Here is how we will name/number future releases* we are currently working on:

6.0.1 is reserved for a possible non-retail release of XS used by an upcoming version of the NetScaler SDX product
6.0.2 is planned as the hotfix rollup + maintenance release post-6.0, targeted for Q1 2012. (This would be the release to target if you are the type who likes to wait for “Service Pack 1” for major releases)
6.1.0 is planned as a new feature release in mid-2012
6.1.1 is planned as the XenServer release to ship with an upcoming major version of XenDesktop, with even more useful features for XenDesktop and XenApp.
6.5.0 is planned as the next “Major” release, where we aim to do things like upgrade the Dom0 OS, integrate the new version of the Xen hypervisor, and add a number of new features.