Hi,
I have noted down some of the details regarding the idea to implement the functionality of apt-get as a filesystem exploiting the flexibility Hurd provide to implement filesystems here.
http://hurd.in/bin/view/Hurd/UniversalPackageManagerCurrent idea is to use stowfs to implement package management. Stowfs tries to implement the role of dpkg in the filesystems, we may even use stowfs internally in the universal packagemanager (or whatever the name we come up).
Many of the details we need to discuss as it is not clear fully.