Using Rails 3, I\'m trying to figure out what I think should be pretty straightforward...
I have 2 gems that require 2 different versions of the same gem dependency.
I'd go for what @BaroqueBobcat suggests. I just want to add that - if you need the latest Twitter gem and can't wait for the maintainer of Groupon2 to update his gem - you can fork the Groupon2 on GitHub, update its gemspec, see if it still works by running its tests (and try to fix it if it doesn't) and include your own version using its Git URL in your Gemfile like so: gem "groupon2", :git => "https://github.com/yourgithubuser/groupon2.git".
If you want to be nice you can offer your changes to the maintainer of Groupon2 with a pull request for bonus points :)