The ccr artifact is a research software prototype to provide a concrete context within which to explore those issues.
April 2011 will mark the fifteenth year of the ccr central key server's lifetime here at keys.ccrcentral.net (although due to various regrettable downtimes, it's only had some fourteen years and counting of actual 'experience'). During that time, the artifact has gone from version 0.1.87 to version 0.6.5.