Running Fedora Core 6, latest updates, Gnome desktop, a Matrox P650 card with unofficial Parhelia drivers v18.104.22.168 from Alexander Griesser (see here if you need them: http://www.tuxx-home.at/archives/2006/12/11/T22_52_32/
I have managed to get the drivers installed and one of my HP L2045w flat panels running at 1680x1050.
I can not figure out how to get dual head support working or to rotate into portrait mode.
I am thinking maybe I could get into 1050x1680 dual head if I hand-edited the xorg.conf file. But I do not know what I'd need to do to make this happen.
I've tried using Gnome GUI admin forms for setting rotation and dual head. But it does not work:
1) Gnome System | Preferences | Screen Resolution dialog box has Rotation grayed out.
2) Gnome System | Administration | Display brings up a "Display settings" dialog box. But if I try to change settings there including the "Use dual head" and hit Okay the dialog does not close and it has no effect on the next reboot. Also, this dialog does not provide a rotate option.