http://www.libvirt.org/remote.html#Remote_limitations says:
Limitations
* Remote storage: To be fully useful, particularly for creating
new domains, it should be possible to enumerate and provision storage
on the remote machine. This is currently in the design phase.
* Migration: We expect libvirt will support migration, and
obviously remote support is what makes migration worthwhile. This is
also in the design phase. Issues to discuss include which path the
migration data should follow (eg. client to client direct, or client
to server to client) and security.
IMHO this is outdated information, because libvirt supports both
features now. So both should be removed from the website as they could
misinform newbies.
Matthias