ending the tyranny of unix permissions
In Debian, we work on developing a unix-style operating system, and when the project was getting started, the obvious way to deal with delegating powers to various people was naturaly to use standard unix permmissions on our master server. So the list administrators were the only people who could write to the list configs and archives, the BTS admins were the only ones who could write to the BTS, the archive admins were the only ones who could manipulate the archive, the build daemon admins were the only ones who could modify various bits of that stuff, etc.
As time went on, these services were split off to seprate machines and in some cases access to the machine running a service was limited to the maintainers of that service, again in a way that would be familiar to unix admins everywhere. But as time went on and things like revision control systems became available, Debian also began to make some choices that didn't involve unix permission or host based security.
The best example of this is the Debian bug tracking system, which allows anyone to manipulate any bug status in any way without any authentication at all. It works because the BTS keeps a record of all changes, and informs interested parties about changes, so vandalism or accidents can be reverted. Aside from spam, vandalism in the BTS is such a rare problem that I cannot think of an example. Thus the Debin BTS partakes somewhat of the WikiNature, although it predates the wiki by a long time.
The archive itself only uses unix permissions at its core, while the upper layers do not partake of them: Any maintainer can upload any package and superscede data in the archive automatically, although actual unix write permissions are very limited. The archive administrators use archives of old versions of packages, automated checks, and forced manual review of certian classes of packages (such as NEW) to limit this so that Developers don't make messes. Social norms are used to avoid other problems.
The Debian website is in an interesting period in its history. It's been maintained in a way that mostly avoids unix permissions for a long time, by keeping it in CVS and building it automatically. However, for reasons that I suspect have never been adequately explored, not all Debian developers can commit, you have to be in the webwml group. Though gaining access to the webwml groupo is trivial for any Debian developer. But the most interesting thing is that Debian now also has an official wiki, which is open to editing by all, and that increasingly it is used for at least the more fluid and development-based website stuff. For example, the debian-installer home page is a thin stub giving the essential information and links, and mostly linking to the wiki for the rest.
The debian-installer project itself occupys another point on the scale between locked down unix permissions and free modification by all. People have to get an alioth account and demonstrate basic competance to get debian-installer write access, but don't need to be Debian developers or spend more than an hour or so to get access. Once you have access, you can change anything in svn (and everything is in svn) we don't limit write access to parts of the project. We avoid malicious commits through patch review.
I could give many more examples of subsystems in Debian that exist at different point in the spectrum between locked down unix permissions and a wiki. There seems to be a definite pull toward moving away from unix permissions, once ways can be found to do so that are secure or that allow bad changes to be reverted (and blame properly assigned). Cases of moving in the other direction are rare (one case of this is the further locking down of the Debian archive server and BTS server after the server compromise last year).
Anyway, the point of this is that, if you survey the parts of dealing with the project where Debian developers feel most helpless and unempowered, the parts that are over and over again the subject of heated discussions and complaints, you will find that those are the parts of the project where unix permissions still hold sway. This can range from simple cases such as a cron job that only one person can look at and modify, to various data files that could perhaps be kept in svn, but aren't, all the way through to stuff like the Debian keyring. I would love to see a full list developed, although many of the things that remain are obscure little corners like certian blacklists in the BTS, bits of the buildd infrastructure that only a half dozen people know about, etc.
The challenge, then is to find ways to open things up to everyone, without throwing security out the window. It has to be done a piece at time, and some of the pieces that are left are the ones most resistant to this change. I hope that people can keep this progression away from unix permissions in mind while working on Debian infrastructure.
(If I ever ran for Debian Project Leader (which I won't), this would be one of the areas that I would be sure to investigate basing my platform on. Speaking of which, it's nearly election season again, isn't it?)
 The best solution I have found to this common problem so far is simply to keep the cron job in svn with everything else, and if someone modifies it, review it and update it via semi-automated means (some simple command). There are probably better ways to do it.