Mirroring and hosting rubygems.org

[hemm...@yahoo-inc.com]

We are trying to create a local mirror of rubygems.org interal to our organization, so that we can pull gems from the local mirror instead of rubygems.org. We will be mirroring all versions of all gems available on rubygems.org, as well as adding gems private to our organization. The rubygems resources page (http://guides.rubygems.org/run-your-own-gem-server/) mentions gem server, geminabox, and gemirro as different alternatives to do this.

What are the recommended ways to mirror and host gems from rubygems.org?
What kind of rate limiting does rubygems.org implement? What precautions should we take when we do the initial mirror of all of the gems (should we throttle the download or space it out over time)?
Is there any way by which rubygems.org can notify us of updates to existing gems, or do we have to periodically check for changes? What is the recommended duration between these checks?