The acts_as_solr plugin has moved from Subversion to Git to allow a faster and easy way of collaborating.
If you haven’t already done so, check out acts_as_solr on GitHub at http://github.com/railsfreaks/acts_as_solr
Here's the official announcement http://railsfreaks.com/2008/5/4/acts_as_solr-is-now-on-github