We moved the source code from Google Code to GitHub: Now it’s here: https://github.com/copper-engine/copper-engine
Google Code served us well one year now, but we found that GitHub has some very attractive features: better issue and release management, free webspace (GitHub pages), a nicer wiki. Plus, of course, the first-class support for Git, the new version control behemoth we all love.
Please let us know if anything is missing! E-mail to firstname.lastname@example.org.