This problem isn't specific to Rails 3.1. At some point, your frameworks need to be upgraded, because at some point the developers stop supporting your version.

This problem isn't specific to Rails 3.1. At some point, your frameworks need to be upgraded, because at some point the developers stop supporting your version. Django announced recently that 1.7 would no longer be getting security fixes. The question is: how much will it cost to upgrade when the day comes? Frameworks and communities that encourage less magic and less dependencies will always be less costly to maintain.