By Hyshio 2010-12-01 06:09:41
I also found this bit of info since apparently Omega weapon will be back in this update.
http://finalfantasy.wikia.com/wiki/Omega_(Enemy)
As with other characters, like Shinryu or Gilgamesh, it is possible that several of the "Omegas" that appear in the series are actually the same entity across several games, traveling between worlds via The Void. According to the Urutan-Yensa Bestiary entry in Final Fantasy XII, Omega Mark XII was created by an inventor for the request of an unknown Patron to defeat some kind of monstrous Wyrm . After giving birth to a brood of Weapons, the original Omega escapes after Farrister and his patron had a falling out. Dissidia Final Fantasy refers to Omega as a powerful machine created by an ancient civilization to destroy another powerful entity, and that it now travels dimensions aiming to complete this objective. Omega Mark XII is also said to be a traveler of the dimensions, and "was a learning, growing entity, almost alive."
All this may suggest that the incarnations of Omega appearing across the series are either the same entity traveling between worlds, or that they are shades of the original Omega, as the Final Fantasy XII information on Omega implies, that were sent out to different worlds by the original Omega that created them. Based on Final Fantasy XII stating that Omega was meant to destroy a powerful Wyrm (or Dragon), and Dissidia stating that Omega was created to destroy a "massive power", it may be that Omega's objective is to destroy Shinryu, a powerful dragon that often appears parallel Omega as another superboss and who also has the power to travel between dimensions.