Just minutes after posting that LGD announced it will start mass producing flexible OLEDs, here comes Samsung with their own announcement. It turns our that Samsung Display is already mass producing 5.7" flexible OLEDs and supplying them to Samsung Electronics. Samsung will release the first flexible OLED phone (probably a Galaxy Note 3 Special-Edition) "within days".
Samsung's 5.7" panel offers Full-HD resolution and it is only 0.12 mm thin. It weighs 5.2 grams and has a curvature radius is 400 mm. So while LG's flexible display is larger at 6", it is much thicker (more than three times thicker at 0.44 mm).
Samsung Display is producing those OLEDs at their 5.5-Gen line. They currently have a capacity of about 8,000 sheets per month, which is about 1 million 5" panels a month at 100% yields. Obviously yields won't reach 100%, some of the line's capacity will be used for R&D activities, and they chose to produce 5.7" displays - which means total capacity will probably be a few hundreds of thousands of panels per month.