I have two servers running debian sarge (stable). Etch is nearly ready to go stable (in hard freeze) so I decided to test the upgrade on the least important box.
This box has apache, samba, gnump3d (music).
First I switched all the apt sources over to etch.
Then I ran
apt-get update, followed by an
aptitude update (aptitude seems to get confused with sources changes without the apt-get update).
aptitude dist-upgrade. This threatened to remove my kernel image (2.6.8) and not install a new one.
aptitude install linux-iamge-2.6.18-686. This wanted to install a new kernel and remove the old one. Not so good - but - if necessary then OK. However - during config it moaned about this being a first time lilo install (all my boxen run grub instead). So -
aptitude install linux-image-2.6.18-686 grub and finally it installed a new kernel.
Reboot to the 2.6.18 kernel (the 2.6.8 was gone at this point) and it booted OK. Now re-run the dist-upgrade. This worked for all packages except ssh. That had problems - couldn't install openssh-server and openssh-client. I had to purge ssh and then install these two packages to get them in place.
Finally - the box is running etch.