Back around 1999, I was really interested in getting all of Debian imported into CVS (ugh!) so we could have all the benefits of pervasive version control. I've always been sad it didn't happen, especially since ubuntu did it. Although they seem to get less benefits from it than I would have thought at the time, go figure.
I actually feel though that the model Debian has developed with alioth and now with VCS- fields, in which packages use version control, and debian integrates support for it without mandating it, or mandating which version control system is used, is has better legs than ubuntu's model. Ubuntu's model potentially leaves you where freebsd is now, nursing a cvs equivilant along as the world has moved on.
Except, well, Debian actually picked a different version control system, and has been stuck with it for years. I refer to the diff, which is great for passing patches around by email, but not so great as a mechanism for recording the history of changes needed to debianise a package. So we have this whole set of things piled on top of the diff, like the loathsome dbs. We also have this whole set of problems in the source package format that cannot be expressed by diff and have to be messily worked around, like not being able to add/modify binary files, and not being able to (re)move files.
(Wig and Pen addresses some of the worst limitations of the current format, but AFAIK noone is working on implementing support for generating Wig and Pen format packages, since doing so is unavoidably complicated.)
Once I started looking at the diff in .diff.gz as a version control system, the natural thing was to think about adding support to other revision control systems, following down our path of debian supporting maintainers who choose to use a different one. So I arrived at the idea of a .git.tar.gz.
Let a debian source package consist of just a .dsc and
package_version.git.tar.gz, which contains only package/.git/*. Making
changes to the source becomes very pleasant, since you can commit any
change you like and not have to worry about how it will be repesented in
the .diff.gz. And of course there's all kinds of benefits of having the
history and branches and tagged upstream source available in there. Far too
many benefits to list here, and only a few downsides.
I look at this as very much of an evolutionary change, not a revolutionary change, to the debian source format. Most packages will continue to use .diff.gz for a long while, but packages whose maintainers chafe under that format will have another one to choose from.
So, well, I implemented it. A dpkg-source that understands this format is
available in the sourcev3 branch at git://kitenet.net/dpkg. I'll
be posting some technical details and the patches to debian-dpkg, and I've
put a FAQ about it in the wiki.
A sample dpkg source package built using this is temporarily here. This demo package includes only the last 200 commits to the dpkg git repo, so it's more than 1 mb smaller than dpkg's normal .tar.gz!