Listaller is a project that aims to replace the way people currently install applications. Specifically, its developers think adding repositories (for example, PPAs) to get a new application or the newest version is an overkill, it’s a security issue since it mostly means someone has full on root access to your computer.
To solve this, they’ve come up with a way to install applications (low level libraries aren’t supported, i.e. you won’t be installing X with this) without requiring changes on anything installed using your system repositories. Their solution is simple enough: Apps installed by the user are dependent on 3rd-party libraries, those 3rd parties libraries are installed on a different layer (on top of your system layer) without making any changes to your system layer. The following images should make things clearer:
Software relations now
Software relations with Linstaller
If you want to test it out, you can download the tarballs from here or, if you want to know how irony tastes like, you can add ppa:ximion/packagekit to your repositories (it’s maintained by one of the developers themselves). Or you can hit the source for more information.