rpm13; Hi !
The short answer is no, with the implementation of upstart, there is no method available to log the startup messages. However one may see the boot messages. In 12.04 I do it like this:
Edit /etc/default/grub (make a backup copy first, Murphy's law applies to computers too)
Change these lines to this:
sudo cp /etc/default/grub /etc/default/grub-orig
gksudo gedit /etc/default/grub
Save and exit
On boot; ctl-s will pause, ctl-o resume boot (maybe). Might try the scroll lock key.
Other means: after booted to the gui, start a terminal and stop lightdm:
Then ctl-alt-f7 will have boot messages on what was the GUI interface.
sudo service lightdm stop
to restart the desktop.
sudo service lightdm start