Hey!
One of the few issues I have found with building Snow Leopard images with InstaDMG is that the AirPort network interface is disabled until you open System Preferences > Network after the first boot. I asked larkost (Karl) about this, and he gave me a great tip about using the networksetup command in a launchd to run at first boot (Thanks Karl!).
/usr/sbin/networksetup -detectnewhardware
Is there a better way to detect available network interfaces on first boot? This seems to happen automatically in Leopard, but not in Snow Leopard. Any idea why? I skip the Apple Setup Assistant in both my Leopard and Snow Leopard images.