One of the major features of an automated installer is the ability to choose all options up front, then press "Go" and let the installer do the rest. All the user interaction happens at once, with no waiting in between. The Ubuntu installer does quite well with this, except for one thing: if the user wants to reboot after the installation, they must wait until the installation process has completed, and then press the reboot button at the end. It should be possible to make this decision at the same time as all the other installation options at the beginning. There should be a check box during the installation process, under the progress bar, that says something like "Reboot when the installation has finished."
If this is implemented, then there remains only one obstacle to a true set-and-forget installation in which the user could set the install options, press go, and come back half an hour later with the computer already booted into the newly installed Ubuntu (not still waiting in the Live CD). This is the need to press enter at the end of the reboot process. This is probably harder to solve, because this is a feature for people who need to eject their CD before rebooting due to BIOS boot order concerns. Perhaps checking the checkbox described above should reveal a second checkbox that would disable this end-of-reboot pause.
Triaged to Confirmed. Reporter makes valid points with suggestions. Since Importance has been assigned to wishlist, it will probably require some major overhaul of ubiquity.