You can already say "foo _1.2.3_ bar". That said, I see little benefit in making rubygems bundler-aware, and I think it would constrain both projects in undesi

You can already say "foo _1.2.3_ bar". That said, I see little benefit in making rubygems bundler-aware, and I think it would constrain both projects in undesirable ways. For example, you propose rubygems checking for a Gemfile, but that is only a convention. Bundler supports an env var to identify the location of a gemfile. So right away, rubygems would need to support both of these techniques. When bundler adds new and better ways to do this, rubygems would have to be updated to keep up. Or, perhaps, it wouldn't, in which case the projects would fall out of sync. Bundler already offers us simple ways to do this. See http://yehudakatz.com/2011/05/30/gem-versioning-and-bundler-doing-it-right/ http://yehudakatz.com/2011/05/30/gem-versioning-and-bundler-... (including the comments) for more information.