Cell by Stephen King
Stephen King has made a point of re-imagining most of the big-ticket monsters in the horror genre, and sometimes he surpasses all previous efforts, as with the ghost story in The Shining, and sometimes others lap him, such as Anne Rice and her vampires. I think that King wins the Zombie sweepstakes with Cell, Shawn of the Dead notwithstanding.
Cell starts where Dean Koontz says good stories should: At the latest possible point in the story. Our hero is walking down the street, suddenly everyone who is talking on a cell phone goes batshit. Hilarity ensues.
For those who like a teaser, in one of the early episodes our hero bumps into an evangelical Christian who's raving about the end times. I greatly enjoyed King's finally addressing that scenario, since he didn't really the last time he destroyed the world in The Stand (his best, so far, btw, for those of you who've never read him).
No spoilers here, but I just want to say that the ending is one of the more heartbreaking ones he's come up with. Not to say that it's a bummer, or even a happy ending. That's one of the reasons it's so poignant. Maybe true hope always echoes the fear that births it.