Installer.app will crash if you tab to the Agree button in the license agreement, then hit the Space Bar to press the button -- it crashes when you get to the last step (after selecting the destination). Also, the text Click install to perform a basic installation of this software package on the volume "VolumeYouSelected." is up and to the left of where it should be.
This assumes you have the "All controls" radio button selected in the Keyboard Shortcuts tab of the Keyboard & Mouse System Preferences panel. You can toggle this setting from anywhere by hitting Control-F7.
To work around this bug, click the button with the mouse and avoid using full keyboard access in this particular spot. I've only confirmed this on Mac OS X.4.3.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20051221184239173