Physical barriers between each ISOCELL pixel allow 30% decrease in crosstalk and 30% increase in full-well capacity when compared to "conventional" BSI sensors, possibly, S5K4H5YC.
Samples of the 8 MP RWB ISOCELL image sensor are available for customers and mass production of the product is scheduled for Q2 2015. Incidentaly, the S5K4H5YB has already been announced a year and a half ago. By that time, Samsung said "The S5K4H5YB is currently sampling to customers with mass production scheduled for Q4 2013." However, in the earlier announcement, Samsung has not mentioned RWB CFA.
Samsung S5K4H5YB product page says that it's already in production: