After the Fall: Resurrection (ATF:R) is the first in a new science-fiction series by Kingsley V. Montgomery, the author that brought us Scion of the Dark Moon and the rest of the Terralis Legacy fantasy series.
ATF:R takes place on Earth following an alien invasion and the subsequent "fall" of one of their ark-ships into the Pacific Ocean, a near-extinction level event that wiped out most life on the planet and abruptly ended the war between the invaders and indigenous humans.
Two hundred years later, California, where the book takes place is a much changed place. Genetically engineered mutants roam the "Outlands" together with feral dinosaurs (with a great nod to the Jurassic Park books/movies), alien life, cannibals, and rag-tag humans that have banded together to form radically varying cultures.
Several major cultures are mentioned in the book's draft (it is due out in late 2007). The first and perhaps most interesting is the Silicon Republic, with its roots in the technocracy of Silicon Valley. The "Silics" as they are commonly called, are the preservers of technology and they are trying to forge a new nation based on technology and order -- but their culture, after living underground for generations, is as xenophobic and authoritarian as it is advanced.
Another is the Brotherhood of Mutants, a loose collection of mutants that are more akin to American Indians than anything else. They can be brutal and savage, but they see themselves as the rightful inheritors of Post-Fall Earth and have suffered as slaves at the hands of "pure" humans.
Others that are mentioned but not detailed much in the first book are the League of Free Traders, the Angel Free Cities (Los Angeles), Samura, Jeffersonians (drug-dealing militia-like groups) and the Vagans (the remnants of Las Vegas!).
The protagonists are International Space Emergency Force (ISEF - think Coast Guard in space) Marines that spent the last two centuries in suspension following one of the first encounters with the alien skel. They are "thawed out" by the Silics and quickly learn that the world is not what is used to be!
The world is as frightening as it is inventive, sure to please science fiction, military, and action fans.