I think they are. I was researching a famous quote by Victor Fromm that says that millions of people, today, live like automatons. I then came across a definition of "zombie" as a person who "lives like an automaton."
Also, the final scene of Sean of the Dead shows the remarkable similarity between a zombie and a person who has survived the most brain-damaging types of drug addiction (such as PCP) or severe alcoholism.
I think that any image that captures the popular imagination is a metaphor for deeper issues that most of us don't want to address directly. That includes zombies, vampires, and werewolves, these days. It also includes Sherlock Holmes, Superman, and Wonder Woman.