lol! are you serious? I can't tell if you are joking, really bad at sarcasm, or just woefully misinformed, but that statement is patently false! 97% (or more) of all phones use a standard LCD screen. Now I'm not sure about Japan/Korea, but at least in the US/EURO market, I believe there have been less than five phones EVER that have used OLED technology.
Organic LED technology is VERY new and is just starting to trickle into consumer electronics. They promise very low power usage, incredible contrast and color range, very slim profiles, and even flexible displays. Although there is a lot of R&D in progress, the organic light-emitting layer still has a short lifetime (especially the blue component), and the manufacturing yields are still low. But within 3-5 years, I'd guess they will overtake LCD screens in small applications like cell phones.