As my main (Ubuntu 6.06) machine had to go in for a repair, I installed Xubuntu 6.06 on an older system. After adding OOo and Evolution, that system was ready to go.
Copied the .evolution folder from the Ubuntu machine to the Xubuntu machine and found out that some things are 'not there' in evolution:
1)
Had to reconfigure the ISP settings. OK, just typed them in again.
2)
I have several address books but only the main one was available in evolution on the Xubuntu system. As I still had the Ubuntu system, I could export the address books and import them on the other system.

A bit of analysis showed that the address books are stored using 'funny' names like 123456@hostname. This got me a bit worried as restoring a backup after a system crash might give the same problems.

The actual question:
How does one backup evolution's data so a restore is a matter of copying stuff back?

Here's a link to a comprehensive guide to backup and restore Evolution data. It's not difficult and straight forward. Just copying stuff as you preferred.

PS: If you want just to get a backup of the address book you can always export (save as vCard) and import (File --> Import) it later.

And you'd be happy to know there's a suggested plugin for backup/restore in Evo 2.12 series, and is in testing. Hopefully we'll see it soon.

After posting, I found some additional info. Obviously I forgot to copy something (the gconf part). Will keep that in mind the next time.

After reading, I (still) don't think it's a matter of a simple copy as I tried that (yes, I'm stubborn), but will try the link when I get my main machine back.

Thanks for the reply.