rbenv-gemset is an extension for the rbenv ruby version manager that allows you to use sandboxed collections of gems
rbenv-gemset is an extension for the rbenv ruby version manager that allows you to use "gemsets", sandboxed collections of gems. This lets you have multiple collections of gems installed in different sandboxes, and specify (on a per-application basis) which sets of gems should be used.
You can also install gems into a sub-folder in your project directory for easy cleanup later (or easy customization, or testing).