Considering the balkanization of even the Linux binary package market, it's not very likely to happen, both for political and technical reasons.
And not everyone needs to use the same repository either. Again, apt does handle multiple repositories just fine.
And you'd need language bindings for selecting the properly installed package (language modules need to be multi-version capable). Things like "gem 'activerecord', '= 1.4.0'" in RubyGems, or Maven's dependency resolution.
But again, the technical difficulties pale before the political ones. You'd have a much larger chance of success concentration on one platform (e.g. Debian), creating some automatic gem/egg/CPAN converter and then wrapping the language-native tools to use that. Whether that's actually worth the effort…