I wasn't sure I'd ever see the day that the UVa library would, as an institution, agree to open source Blacklight. But they did! [A dirty little secret is that the bulk of it, including a basic example MARC indexer, was open sourced last year during the preparation for the Solr code4lib preconference.]
A few points make this especially thrilling for me - the name Blacklight was my creation, during one of those aha moments (groping through "solar" Wikipedia pages, and UVA radiation popped out, also known as blacklight); the code is licensed under the Apache Software License, contrast this with the GPL license that VUFind is using - big big difference to me at least; and finally... it's Ruby!
Bess has already received one patch to the code, shortly after she announced the release on her blog. This is very encouraging! Open source only works with a community - and the project is already off to a great start.
Blacklight has a long way to go to catch up to the other open source Solr-based OPACs that have emerged over the last year, but it won't take long to catch up given some motivated individuals with some basic institutional support.