Patrick Carey wrote a nice blog on the Citrix blogs about the new features in provisioning that comes with the Excalibur Tech Preview available at this time.
One of the benefits of the updated FlexCast Management Architecture is that XenApp farms can now be deployed and managed from within Studio. This also means they can be provisioned using the Machine Creation Services linked-clone delivery model that has been available within XenDesktop for a few releases now. One of the primary benefits of MCS is the ease in which new catalogs of machines (virtual desktops and now virtual XenApp servers) can be created. Updates to the catalog creation wizards in Studio guide you though the initial roll-out of a virtual XenApp farm. The MCS model provides many of the same single image management benefits of Provisioning Services, but works directly on the storage managed by your hypervisor, so there is no need to deal with PXE or build-out a Provisioning Services deployment. However, this capability is limited to the new Excalibur version of XenApp.
PVS streaming for XenApp farms and desktop catalogs is still an option in Excalibur, providing the enhanced image management capabilities and storage IO optimizations beneficial in larger, more complex environments, though management of the Provisioning Services infrastructure remains in a separate management console. Provisioning Services will continue to provide a centralized image library for mixed environments where multiple “sites” or “farms” of XenDesktop and XenApp are used.
Read more here.