It's been talked about but nothing came of it.

I have a Command Button in ASUI.

Full Screen (name)

sleep 1;/usr/bin/wmctrl -r ":ACTIVE:" -b "toggle,fullscreen" (action)

and a check on (unmap ASUI)

The programs you would like to be in full screen, you could always check the help settings on them.

Example:

/usr/bin/roxterm --help

Based on what it states

/usr/bin/roxterm -f
would launch it full screen.

You then would need to edit the launch file in
/usr/share/applications/hildon/

Post back if you have any luck on this.