Hudson and Jenkins are continuous integration servers. They are both forks of the same codebase created by Kohsuke Kawaguchi, former employee of Oracle, the company which owns the Hudson name.
Since Kohsuke abandoned Hudson to work on Jenkins, we wondered which fork would be more actively maintaned and improved. We can draw some metrics analysing their repositories.
From GitHub perspective Jenkins is the clear winner with 630 vs 175 commits since the fork, 18k vs 12k pageviews, 401 vs 82 watchers and 160 vs 12 forks.
Accordingly to OhLoh Jenkins has fewer users (53 vs 344), but more active contributors (209 vs 131).