Debian

May I suggest an alternative route to that end: Build a small network containing those OSs and applications that you have in production, plus a dedicated server to roll out updates. When the distributor puts new updates online, apply them to the test environment first. If they still behave well after a certain period (eg. 2 weeks), put them on your internal update server, from which your other machines can automatically update. Those that don't work just get skipped.
As for the test environment: if you don't have any special hardware needs, virtualization works just fine (VirtualBox, VMware, ...)

Thanks for you information, this will prolly mean we will schedule all patches for between business times. Though this makes me think of security patches, since you want them to be installed straight away how can u see if a package or patch is related to security issues?

Don't know about Fedora, ... but for Debian there are always 2 update sources (see sources.list)

Code:

deb ftp://ftp.<tld>.debian.org/debian {sarge|etch|lenny|stable} main contrib [non-free]
deb ftp://security.debian.org/ {sarge|etch|lenny|stable}/updates main contrib [non-free]

The second entry here is the update site for security patches that aren't already incorporated into the usual updates. Same goes for Ubuntu (and most other Debian-based distributions)

I already had those links in my sources.list on the test server,

Anyway thanks for the info,