I’ve just put up a short, new article about performing installations of Enterprise-class Linux (i.e., Centos 5.6, Centos 6.0, Scientific Linux 6.1 and so on) via a network.
The basic principle is that you set up your Apache server once to serve up any or all of these distro/version combinations, boot your main server with a small net install CD and then have the main distro install itself by shipping files over the network from the Apache box.
The twist is that if you combine this with Kickstart technology to automate the main installation process, you basically have instant auto-install capability anywhere on the network, with no need to muck about with full-blown installation disks or ISOs. We once had a server at work which only shipped with a CD-ROM drive, whereas I’d downloaded the DVD installation media… this fixes that sort of mess!
As usual, make of it what you will!