[skateinmars]

Yes, you can specify a git repo in your Gemfile (and optional tags/branches) :

    gem "rails", :github => "rails/rails", :tag => 'v3.2.11'

You can also specify multiple gem sources (http://gembundler.com/v1.2/gemfile.html), but usually only rubygems.org is used unless you need a private geù repository.

[robryan]

Yeah the question is, can you specify to grab rails from github with a fallback if it is not up? So the same system it seems to be using with multiple gem sources but on a gem by gem basis like you would do with a github repo.