Firefox 3.0 stable default setup has these features disabled

• direct printing from print preview
• ability to zoom page before printing from print preview
• ability to change printing page orientation (portrait/landscape)

all this can be achieved by setting string print.whileInPrintPreview in about:config as true
(this now defaults to false).

I filed a bug report about this issue here: https://bugs.launchpad.net/ubuntu/+source/firefox-3.0/+bug/245772