Yesterday (March 10, 2010) I participated in a NISO Webinar about identifiers. The resources page associated with it has some good links, and the slides are supposed to be posted soon. I talked about how VIAF, ISNI and ORCID might cooperate, and since VIAF is what I spend a lot of my time on, it got a couple of extra slides.
Currently VIAF has over 10 million personal names in it derived from nearly 13 million authority records from 20 different files. To support the matching we are also managing some 70 million bibliographic records which we match against the authorities and extract additional information (e.g. titles, coauthors, publishers) that can be associated with names.
One of the questions asked during the Webinar was how ordinary libraries can be part of VIAF. If your library is a NACO participant, any personal name records added will flow into VIAF automatically (currently it takes about a month). If your library is in the U.S. and the material was produced in the U.S., VIAF probably isn't going to be a lot of help to you, but if the material has names associated with it from outside your country, VIAF might be of great use in sorting out who is who.
Update (2010-03-12): One thing I forgot to mention during the Webinar is that in addition to OCLC, the British Library and JISC Names project are involved in both ISNI and ORCID.
Also, see the comments about linking the LC/NACO file to ISNI