It seems that Tiger's installer overwrote my /etc/hosts file without asking. If, like me, you add aliases or override addresses using the hosts file on occasion, you won't want to lose this. Make a backup!
[robg adds: In general, if you've tweaked anything in a system-level directory, the chances are good your changes will be overwritten by the installer -- it happens with httpd.conf files, too. Before any sort of upgrade, back up everything, then you can get anything you like back afterwards...]

