As the title implies, the series will focus on Nite Owl, Rorschach, Dr. Manhattan, Comedian, Ozymandias, Silk Spectre, and the Minutemen in the events before the original Watchmen series. It will obviously take place in the original "Watchmen" universe, but won't affect the characters in the best selling graphic novel of all time.
Personally, I think this should be interesting and I'm looking forward to it... we'll be able to see deeper into the "Watchmen" universe and find out more about the characters we love, instead of just watching that movie from a few years ago. Since the original won't be altered, I don't see what all the fuss is about. Find out more info from an interview with J. Michael Straczynski, author of the first part of the series, by following the link above.