With Lucid, the kernel is now telling the BIOS that it supports win7 ACPI features. Part of the Win7 feature set is display configuration changing through win+p instead of the unique key code used by previous versions of windows. The real problem here is that gnome-settings-daemon, the process that listens for display configuration events, only listens for a single key code and not a chord like win+p, and it's not configurable through a gconf setting.
Quirking the kernel is an unsufficient fix because every new laptop would need a quirk. We also pulled the ACPI support from upstream, so we should follow their lead and not behave differently.