it's called "The Passage" by Justin Cronin. I have only read the first few chapters but it is AMAZING so far. This is the book to read according to EW and Oprah. It was featured in a huge way in an email I got from Amazon. If you don't read this book you will be out of the loop!
When I googled the book to find out the release date I honestly saw the phrase "Is this book the next Twilight?" ACK! :)
So get on the bandwagon while it is fresh and new. :)