Thanks for the feedback everyone. Not the unambiguous "Use this, it's the best source" answer I was hoping for, but I've got a better understanding of the issues.
Aubrey - The Italian approach sounds good (and I like the position on the page where the VIAF et al identifiers are rendered), but appears to still depend on the inclusion of the {{Controllo di autoritą}} template which is missing in this case
http://it.wikipedia.org/wiki/Jos%C3%A9_Mujica Not sure if that's just a synchronization issue or something where people need to manually noticed that the data is available in VIAF and include it (seems like a job for a bot). Also, for Max's example, it only includes one of the two different VIAF identifiers:
http://www.wikidata.org/wiki/Q18391
Max - I'm not familiar enough with the universe of possible technical options or the Wikipedians culture to really have a valuable opinion, but that sounds like it would probably be too aggressive from some of the comments that I've read along the lines of "not sure if I want to invest the time to learn how to edit things in a new (ie Wikidata) way."
Clearly data that's not visible isn't going to get reviewed or corrected. The trick is to make it visible in a way that makes the local editors still believe they have control.
Tom