Overview:

Quetzalcoatl is an Aztec sky and creator god. The name is a combination of quetzalli, a brightly colored Mesoamerican bird, and coatl, meaning serpent. He is often referred to as The Feathered Serpent and was connected to the planet Venus. He was also the patron god of the Aztec priesthood, of learning and knowledge. Today Quetzalcoatl is arguably the best known Aztec deity, and is often thought to have been the principal Aztec god, however he was one of several important gods in the Aztec pantheon.

The cult of the serpent in Mesoamerica is very old; there are representations of snakes with bird-like characteristics as old as the Olmec preclassic (1150-500 BC). The snake represents the earth and vegetation, but it was in Teotihuacan (around 150 BC) where the snake got the precious feathers of the quetzal, as seen in the murals of the city. The most elaborate representations come from the old Quetzalcoatl Temple around 200 BC, which shows a rattlesnake with the long green feathers of the quetzal.

Quetzalcoatl is often associated with Ehecatl, the wind god, and represents the forces of nature, and is also associated with the morning star (Venus). Quetzalcoatl became a representation of the rain, the celestial water and their associated winds, while Tlaloc would be the god of earthly water, the water in lakes, caverns and rivers, and also of vegetation. Eventually Quetzalcoatl was transformed into one of the gods of the creation (Ipalnemohuani). The Teotihuacan influence took the god to the Mayas, who adopted him as Kukulkán. The Maya regarded him as a being who would transport the gods.

Practices:

The worship of Quetzalcoatl sometimes included animal sacrifices, and in most traditions he was said to oppose human sacrifice. It is believed that the Toltecs had a dualistic belief system. Quetzalcoatl's opposite was Tezcatlipoca, who, in one legend, sent Quetzalcoatl into exile. Alternatively, he left willingly on a raft of snakes, promising to return.

The Aztecs turned him into a symbol of dying and resurrection and a patron of priests. When the Aztecs adopted the culture of the Toltecs, they made twin gods of Tezcatlipoca and Quetzalcoatl, opposite and equal; Quetzalcoatl was also called White Tezcatlipoca, to contrast him to the black Tezcatlipoca. Together, they created the world; Tezcatlipoca lost his foot in that process. Along with other gods, such as Tezcatlipoca and Tlaloc, Quetzalcoatl was called "Ipalnemohuani", a title reserved for the gods directly involved in the creation, which means "by whom we live". Because the name Ipalnemohuani is singular, this led to speculations that the Aztec were becoming monotheistic and all the main gods were only one. While this interpretation cannot be ruled out, it is probably an oversimplification of the Aztec religion.

Attributes:

Quetzalcoatl was often considered the god of the morning star, and his twin brother Xolotl was the evening star. As the morning star he was known by the title Tlahuizcalpantecuhtli, meaning "lord of the star of the dawn." He was known as the inventor of books and the calendar, the giver of maize (corn) to mankind, and sometimes as a symbol of death and resurrection. Quetzalcoatl was also the patron of the priests and the title of the Aztec high priest.

Most Mesoamerican beliefs included cycles of suns. Usually, our current time was considered the fifth sun, the previous four having been destroyed by flood, fire and the like. Quetzalcoatl allegedly went to Mictlan, the underworld, and created fifth-world mankind from the bones of the previous races (with the help of Chihuacoatl), using his own blood, from a wound in his penis, to imbue the bones with new life. His birth, along with his twin Xolotl, was unusual; it was a virgin birth, to the goddess Coatlicue. And according to Wikipedia,

Though not official church doctrine, many members of the Church of Jesus Christ of Latter-day Saints believe that Quetzalcoatl was originally Jesus Christ, whom they teach visited the Mesoamerican natives after his resurrection.

Lately, some sites online have begun associating the end of the Mayan Calendar in 2012 with the possible return of Quetzalcoatl to Earth. Given the flavor of the Aztec and Mayan Deities and their interactions with humanity, I doubt the Central Americans would have seen it as a message of hope.