As was reported before, Samsung has unveiled a 4.99" Full HD AMOLED panel (440PPI). This panel will go into production in Q1 2013, and will probably be used in their upcoming Galaxy S4 flagship phone:
Samsung managed to achieve such a high pixel density using a modified FMM technology. According to Anandtech, Samsung also adopted a new material that makes these AMOLEDs 25% more efficient. This means that Samsung finally adopted UDC's green PHOLED materials in the new panels.
It's still not clear what kind of pixel scheme is being used here - Pentile or RGB (or maybe modified-RGB as used in the Note II). The S3 has 306 ppi (4.8" 1280x720, PenTile) and the Note II has only 267 ppi, 5.5" 1280x720 - but without PenTile.