After updating to 12.10 today, my xorg.conf doesn't seem to be respected by Quantal. Not sure if this is a 'bug' or whether it's just an adjustment I have to make due to changes in the OS.

When logging in, it seems Ubuntu is now recognizing only one 3840x1080 screen named "Matrox" and maximizing windows spans them across both screens. In 12.04, this configuration file successfully allowed me to override the data provided by my TripleHead2Go and maximize windows to a single monitor.

Any ideas or where to start on trying to debug this?

After a bit of searching, I tried to make changes according to the update here: http://www.phoronix.com/scan.php?page=news_item&px=MTEyMDk

Here's where the config file sits currently:

Section "ServerLayout"
  Identifier     "Layout0"
  Screen      0  "Screen0" 0 0
  InputDevice    "Keyboard0" "CoreKeyboard"
  InputDevice    "Mouse0" "CorePointer"
  Option         "Xinerama" "0"
EndSection

Section "Files"
EndSection

Section "InputDevice"
  Identifier     "Mouse0"
  Driver         "mouse"
  Option         "Protocol" "auto"
  Option         "Device" "/dev/psaux"
  Option         "Emulate3Buttons" "no"
  Option         "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"      
  Identifier     "Keyboard0"
  Driver         "kbd"
EndSection

Section "Monitor"
    # HorizSync source: edid, VertRefresh source: edid
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "Matrox"
    HorizSync       31.5 - 80.0
    VertRefresh     59.9 - 75.0
    Option         "DPMS"
EndSection

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "GeForce GTX 260M"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    Option         "nvidiaXineramaInfo" "true"
    Option         "nvidiaXineramaInfoOrder" "CRT-0"
    #Option         "metamodes" "CRT: nvidia-auto-select +0+0"
    Option         "nvidiaXineramaInfoOverride" "1920x1080 +0+0, 1920x1080 +1920+0"
    Option         "Stereo" "0"
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection