I see a lot of comments about refresh rate at 600HZ so I felt the need to comment because I am sure it's more marketing ploy then anything else. (PLEASE CORRECT ME IF I'm WRONG)
Most sets operated on 60HZ interlaced (30HZ each for odd and even pixels)
When LCD's were introduced they were prone to ghosting effects especially in film (because film material is recorded at 24p). Basically the film would produce 24 frames, while the screen would refresh at 30HZ for odd and even pixels... sooo, long story short this process of 3:2 pull down created what is called "FILM JUDDER"
Manufacturers introduced 120HZ and later 240HZ... these numbers divide evenly with 24p (5, and 10 respectively) supposedly reducing the FILM JUDDER, although based on professional reviews by CNET and others the difference is very subjective.
Plasma TV's have no such issue with refresh rate because their cells "recharge" over 1000 times faster then any LCD TV... However, as a marketing ploy they added the 600HZ refresh rates to advertise their technology. This 600HZ essentially represents 10 sections of a screen operating at 60HZ each (called a sub field)...
I know very little about OLED technology, but I suspect that it is certainly another marketing ploy to make consumers think that based on numbers (120HZ versus 240HZ versus 600HZ), they are getting a significantly better product.
Fact is, I own a samsung plasma (PN50B650), samsung LCD (LN46B750), and a samsung LED (UN55B7000)... and for the most part I see no difference in quality among ANY of these sets. (LCD's due tend to have a bit of blurring, and LED's tend to have a bit of blooming... but both issues are negligible, and only noticeable when I put them all side by side)