TimeVault is almost a backup application. TimeVault is a user interface for a bunch of Linux utilities and copies directories with the ability to copy only changed files. One day TimeVault will be complete and out of beta. For now it is an experiment in progress.
TimeVault is available at launchpad.net/timevault.
TimeVault is at version 0.7 at the time of writing this article. I did not find a roadmap for version 1. TimeVault might develop the way you want or it might not. The main reason for TimeVault is the availability of something similar on the Mac. You can expect TimeVault to get all the features of the Mac application.
TimeVault is based on the Python programming language and may be the best choice if you are Python programmer because you can contribute enhancements.