This is a very good question; what I want is basically a program that will mirror my boot disk nightly to a seperate partition, preferably using a comparison copy rather than re-copying everything to reduce the time and disk access.
Under 10.3 I was using CCC's Psynch/scheduler combo to do this. Worked great--totally transparent, no fuss, even worked if my wife's accout was the currently active one. There was only one problem: if the computer was off or asleep at the scheduled time, the backup wouldn't execute.
Since there is no CCC under 10.4 yet, I started looking for alternatives. One option is a nice Preference Pane called Deja Vu. Reasonably easy to set up, seemed to work pretty well, and not too expensive at $25.
Then I gave Lacie's free SilverKeeper a try. It looks old and crusty, but it's free, was just updated for Tiger, and appears to produce a perfectly good bootable backup, including doing a comparison, instead of just a complete copy. More useful still, it will wake the computer from sleep for the backup, which is really nice. You can also set it to clone on startup, in case the computer was off, but this can get annoying if you're installing stuff or troubleshooting.
Only issues I have with it are that it's not "silent" (it launches a little app to do the work, though it auto-quits when it's done), and it doesn't seem to work quite right if the account it's installed under isn't the currently active one (it'll launch, but won't run).
Synk is also quite nice, and has some great features for saving deleted documents, but it ins't designed to produce bootable clones, so it's out, too.
So far SilverKeeper seems good enough, though I do yearn for a "perfect" solution some day.
Tip: If you backup the way I do, set Spotlight to ignore the backup drive and make sure to tell your backup program to ignore the .SpotlightV100 folder (or whatever it's called) when cloning.
