CoV can be standalone, you won't need Heroes to play it. However, I just got a newsletter in my inbox that says that for those who do have Heroes, you won't need to pay extra for Villains... there was much rejoicing in my mind. not out loud for I was at work. But yes, I have the newsletter to prove it, and it made my friend want to reinstall City of Heroes for that very reason. Oh, nothing will get done on my time.
Incidentally Rach, I'm sorry I missed our Guild Wars appointment. Please forgive, I was careless. :( I won't make those kind of promises anymore.