So, do you have to ask someone's permission before listing them on your acknowledgments page?
Aimee M. Sims
No, not unless you plan on saying something scandalous about them. Of course, then again, one person's scandalous is another person's praise.
I'd say it's not a legal requirement, but letting that person know in advance they will be on the acknowledgement page is a polite gesture. They may wish to decline for some reason, and if so, you should graciously accede to that request.
I agree with Tony, and would just like to add:
Contacting a person because they may with to decline is certainly the best reason to let them know their name will be in print, but another good reason is to use the opportunity to elaborate directly upon your expressions of gratitude.
Why do you want to give them thanks? They probably know, but it (almost) never hurts to say it again in formal communication. If you have had a good working, or personal, relationship with someone, it can also help reinforce that positive connection that was developed, and expanded upon.