Note that we never really had a clear name for the XAPI project. The project was initially named after the Xen Cloud Platform, which is essentially a distribution of the Hypervisor, the XAPI toolstack and various other components. Later, the project also delivered packages into Linux distributions. This has created some confusion in the community! To make this clearer, the project team proposes to name the project after the XAPI toolstack. In other words, the project would be named after the codebase instead of one deliverable that the project produces.
Последняя версия Xen Cloud Platform - 1.6, и, насколько я понимаю, сейчас достаточно скачать XenServer и получить XAPI.