Great to see that there's going to be a tutorial on "How to build a digital library using open-source software" [1] at the upcoming ACM Hypertext '00 [2] conference. Reading through the speaker's bio I found Greenstone [3], nzdl.org [4]'s collection backend. Looks like several implementations are running already, too. It would be great to post a conference report from a willing attendee... (hint hint :)
Links:
[1] http://www.ht00.org/t10.html
[2] http://oss4lib.org/www.ht00.org
[3] http://nzdl2.cs.waikato.ac.nz/fast-cgi-bin/library?e=p-0--00-prompt-1--101l--1-en-50---20-gsdl---1-01-w-0&a=p&p=gsdlsoft
[4] http://www.nzdl.org/