Red Hat (where I work) has a large team of people dedicated entirely to virtualization, so for that use, particularly higher-end server virt, it's getting very good.
http://people.redhat.com/~rjones/virt-top/
http://libguestfs.org/ has a lot of OCaml for internal stuff. The tools are written in Perl, but I wish they were written in OCaml :-)
http://people.redhat.com/~rjones/guestfs-browser/
Another forthcoming tool which I can't mention yet.
More projects here from the company I used to work for:
http://merjis.com/developers
Red Hat (where I work) has a large team of people dedicated entirely to virtualization, so for that use, particularly higher-end server virt, it's getting very good.