The release today of Xen Orchestra 4.12 brings two main features: continuous delta backups and continuous VM replication. The continuous delta backups allow you to only export delta blocks after the initial full export, similar to "forever forward incremental backups", and makes for lightweight backups by exporting only the changed blocks. The continuous VM replication allows for streaming them at regularly timed intervals to a distant Xen Server storage.
Xen Orchestra 4.12 also makes it easier for creating multiple VMs, autobooting VM support, and other improvements and bug-fixes.
Coming up next is the Xen Orchestra 4.13 release, which is said to be one of the last prior to Xen Orchestra 5.0. More details via the Xen Orchestra blog.