Maybe i'm the only one...
I think everyone agrees that one should
- use a file repository
- do builds from the repository (and in a clean environment)
- use a continous testing server (e.g. cruise control) to see if anything is broken after your "fixes"
But no one cares about automatically built versions.
When something was broken in an automatic build, but it's not anymore - who cares? It's a work in progress. Someone fixed it.
When you want to do a release version, you run a build from the repository. And i'm pretty sure you want to tag the version in the repository at that time and not every six hours when the server does it's work.
So, maybe a "build server" is just a misnomer and it's actually a "continous test server". Otherwise it sounds pretty much useless.