Mark Miller wrote on the dev list:
I'd like it for some things if we actually kept the versions somewhere else - for instance, Hadoop dependencies should match across the mr module and the core module.
Perhaps we could define versions for dependencies across multiple modules that should probably match, in a prop file or ant file and use sys sub for them in the ivy files.
For something like Hadoop, that would also make it simple to use Hadoop 1 rather than 2 with a single sys prop override. Same with some other depenencies.