I have an external LCD hooked up to my MacBook Pro 5,5 running Lion. I have major aliasing on the external monitor in every application. Using the commonly recommended
defaults -currentHost write -globalDomain AppleFontSmoothing -int x (with any value 0-4) has no effect on restarting applications or rebooting. The monitor is running at its native resolution, 1440x900, although I had to use SwitchResX to get OS X to recognize this resolution.