Upgrading A Headless Server?

Paul Bristow writes "I've been using a Headless Linux server at home for years and years, but I always find myself putting off doing a distro upgrade. It always means digging out the old graphics card, keyboard and monitor, dusting them off and plugging them in, just so I can have a console to upgrade on. Are there any linux distributions that will allow remote upgrades? You know, log in as root viua ssh, webmin, whatever, run upgrade prog, remotely reboot, off we go. ;-) I know I'm not the only one running a headless server, and I *know* how stable it is, but occasionally RedHat (in my case) come out with a nice new feature that I might want to upgrade for. Also, with just one server it might just be possible, but how do you upgrade a headless server farm?"

Nik posted this relevant article back in March about the PC Weasel, which sounds like a good way to do this, at the cost of a small hardware investment per box. Are there better ones?