Sorry John, have to disagree with you.Spot metering on modern digital cameras is the ability to adjust the exposure to any particular spot on the screen. This behaviour has been verified by two different Samsung tech support agents already and a demonstrator at a Samsung roadshow late yesterday!
I'm not really here to argue with anyone about the subject, my S3 used to do this and now doesn't. Samsung have indeed confirmed that the S3 works in this way and all I'd like to find out is if some update unwittingly interfered with this function and stopped it working.
And FYI, this is not some super-exclusive Samsung only function. My Google / Galaxy Nexus does it, my iPad 3 does it, my daughter's iPhone does it, my wife's Lumia 800 does it and my youngest daughter's 3 year old Galaxy S does it too!
If your S3 doesn't do it, then it's not working properly and I'd suggest contacting Samsung rather than trying to justify its non-working with an explanation that may lead others into thinking that their S3 camera is working well when, clearly, it's not.
By the way, I too know my way around cameras, having actually earned a living as a press photographer for 4 hell-filled years well over a decade ago.