LinuxPlanet has a column on automatic update features among open source programs. "But in the open-source world, this is all fraught with peril, for several reasons.
The first is that it additionally fragments the community. Distributions are not only cooking up
auto-upgrade features, they're cooking up ones that are incompatible with everybody else's. Red Hat
has one now; Debian has for some time; Caldera's working on one for whatever their next distribution
ends up being, and so on."