I, too, would love something like this. You're probably aware, but it's possible to host private gems in a simple static webserver. We have our CI server copy

I, too, would love something like this. You're probably aware, but it's possible to host private gems in a simple static webserver. We have our CI server copy gems over and run a script that calls "gem generate_index -d /path/to/gems". Completely featureless, of course. Lacks the newer rubygems.org api (so bundler is stuck downloading the whole index), and obsolete versions will stick around without manual intervention (which, if you have too many, is a pathological case for bundler's resolver).