Should we just keep ruby-debug, debugger, et al out of the gemspec entirely by putting them into a group other than :development?

Jeweler has a slightly annoying convention of taking all of the gems in your "development" group and adding them to the gemspec as development dependencies -- but who uses that part of the gemspec? No person or application that I know of. It's purely advisory.

When the name of the gem (or the version that's required) can change between ruby versions, RubyGems has no mechanism for dealing with that ... it's probably best simply to leave it out of the gemspec, especially since it isn't required at runtime (or even, technically, to develop the right_support gem).