True to their word, AUO demonstrated new 4.3" flexible AMOLED panels at the Touch Taiwan 2013 conference. The new flexible panels are thinner than AUO's previous prototypes at 0.2 mm (vs 0.3 mm before). They use a plastic substrate and thin film encapsulation. Here's a nice video showing those flexible OLEDs:
The video also shows other advanced panels from AUO, but unfortunately they did not capture AUO's 5" HD AMOLED displays on show.