This is about:
The documentation should be updated to reflect that the minimum resolution
is 800x600 not 640x480.
Smaller devices are supported through the VNC install.
Related bug: 592809.
Thanks for reporting this.
I have committed a fix for this as detailed below:
Author: David Nalley <firstname.lastname@example.org>
Date: Sun Jun 20 15:43:54 2010 -0400
fixing bug 593362 - minimum resolution is 800x600 instead of 640x480