I have a similar problem with my QUAD 27"iMac (Fall 2010 version)
I'm not the first to have seen this issue but the left half bottom 2/3 of my screen is darker and remains at roughly half the over-all brightness of the screen. This doesn't change regardless of duration of use or what is on the computer (movies etc. or static images) From research it sounds like a backlight problem (Inverter board?)
Unfortunately this occured weeks after the warranty expired and I need to know if this is worth getting repaired or not. I could purchase a seperate monitor for a few hundred dollars that's of equivalent quality as the imac's built in if I can live with the imac assuming the position of my old powermac-on the floor.
Does anyone know about getting a repair quote for something like this? I live in NYC so getting a 27" imac to and from the store will not be cheap let alone the repair of the imac which I wish would have functioned better for more than the year I've had it. I've never had problems with my previous apple laptops or powermac and all have functioned 4+ yrs in their own lifetimes.
Is replacing an inverter board something that can be done on my own or is a hard task?
If it's too expensive I'll probably just dust off my22" samsung monitor which has worked perfectly for years with only the flaw of being 22"