I have recently published an article in Archivaria, the journal of the Association of Canadian Archivists (ACA) that looks at how Archives around the English-speaking world have used Facebook and Twitter as a form of social outreach.
I hope this work will be of interest to those outside the archival community and amongst those who may not have access to Archivaria, so I have decided to share a copy freely in PDF format.
Crymble, Adam. "An Analysis of Twitter and Facebook Use by the Archival Community" Archivaria 70 (Fall 2010): 125-151 [PDF]
Abstract: This paper discusses how the archival community is using social networking services such as Twitter and Facebook as outreach tools. The study analyzes the usage patterns of 195 individual and institutional users over a thirty- two-day period during the summer of 2009. By focusing on the 2,926 outbound links posted to the services during the period, the author shows that use is dramatically different between the three test groups: archival organizations using Facebook, archival organizations using Twitter, and archivists using Twitter. The study shows that archival organizations overwhelmingly use the services to promote content they have created themselves, whereas archivists promote information they find useful. In all cases, more frequent posting did not correlate to a larger audience. By examining how others have applied social networking, archivists and archival organizations can determine a social media outreach platform that is suitable to their institutional needs. This study may serve as a starting point toward a greater understanding of outreach in the digital age.