I don't speak any Mayan, but a Mayan pal told me that it was quite similar to the one spoken today in Yucatán. Yes the lead actor had never spoken Mayan, but other actors there were actual Maya people, and some of them had never even seen a movie before. How cool is that
Now, Nahuatl and Mayan are mainly spoken in Mexico, which is not South America yet (North America is Canada, USA and Mexico), but we are part of Latin America
There are many native Latin American languages that are still spoken. Just Mexico has 62 nowadays. The most widely spoken all over Latin America are Quechua, then Aymara, then Nahuatl and Mayan. historically, I understand that Quechua and Nahuatl were the most influencial ones, because they were lingua franca for the Inca Empire and the Aztec Empire each (followed by Mayan for the Mayan Empire). There are many resources for Mayan, and the advantage of this language over the other ones, is that nowadays the Yucatec Mayan is considered as some kind of standard, because it is the variant with the biggest number of speakers and it has an academy, a dictionary, and it is well preserved in that region of Mexico (Yucatán, along with Quintana Roo and Chetumal). Nahuatl has more speakers than Mayan, and it is spoken in a larger region (the center) of Mexico, including the capital (Mexico City). It has several dictionaries and an Academy for the language. And as you can see, there is a small but active Wikipedia in Nahuatl, and there is none in Mayan. The disadvantage is that there are many variants of Nahuatl, even tho right now there is a big movement to standarize the language as much as possible. This is the first year (2009) the goverment has launched official Nahuatl courses with teachers qualified with a new program called "Método Clemente" (Clemente Method), and that is the one I will start studying in a few days and share with you guys. There are several books written in those two languages, and last year Samuel Becket's "Waiting for Godot" was published in Nahuatl. I am sorry I don't know much about Quechua and Aymara, but you can find lots of info in the web
Si la vida te da la espalda, agárrale las nalgas.