I recently upgraded to Oneric and found that Fn+F8 does not switch displays on Oneric, Dell E6410, Nvidia. I frequently run presentations and need to switch between projector and laptop with minimum fuss, so this key is important to me!
In Maverick, I managed to make it work using
acpi_osi=\\\"!Windows 2009\\\" in grub (as described here: http://www.len.ro/2011/01/e6410-summary/). It's a bit shameful to go into a room of people, plug the laptop and wait 5 minutes to make the change using nvidia-settings. How can I make the Fn+F8 work again?
After a bit of debuging with xev it seems that the acpi_osi has some effect but the videoswitch does not take place somewhere else even if
[ 24182.812] (II) PM Event received: Capability Changed
Maybe there is some other place where the event is not handled correctly.