First off... kids under 13 aren't "supposed to" have facebook accounts AT ALL. (at least that is my understanding). That said, obviously some kids do.
As a parent I would sit your daughter down and BRING UP the issue of facebook, myspace, twitter, and email and talk to her about them! Whether you decide that she is ready, or should have these things or not is between you, your husband and her (to a lesser degree).
I would say that these days technology is much like dating- both topics affect teens, both are multi-faceted and can be enriching AND both can have terrible unexpected consequences if abused- oh, and both are privileges rather than "rights".
Like dating, just because your fourteen year old isn't talking about it to you, that doesn't mean she isn't doing "it" or thinking about "it". Almost every kid that I knew who got pregnant in high-school, had parents who didn't even KNOW they were "that far" in. Kids who get in trouble online are often the kids whose parents have no idea WHAT they are doing online.
So, talk to your daughter about it. IF she gets a face-book, naturally you or your husband should have one as well- be "friends" with her on it, and frequently check in on her profile to see what she is doing and saying there, and who she is friends with.
I have a facebook account, and I use it MOSTLY to keep in touch with old friends and my family members, especially my mom. We share pictures and videos and it is a great tool when you are trying to stay in touch with people from all different time zones. That said, especially with teens.. they need to understand privacy and online ettiquette. As a parent you can teach her important ideas that with matter well into adulthood, and facebook *could* help you instill some of those life skills an personal responsibility.
If you decide to explore the idea, talk to your daughter about the fact that EVERY post can be seen by practically anyone, and if you write something down you shouldn't have it wont just "go away". Also, make sure you talk about what information is not acceptable to post on a profile (addresses, phone numbers, emails, information about your exact location at any given time, family affairs, etc...)
It is in some ways better to guide her in these matters while she still lives under your roof and you still have a say in what she does, than to "ignore" the issue until she gets into college and have her get into trouble there, without YOU around to help her.
If you bring it up and she says "Well, I don't want facebook or email" that is ok too! In some ways it makes your job easy, however that doesn't mean you should not talk about it regardless. Chances are there will be a time when she will use facebook (or whatever the newest site craze is) and she will need those words of advice and caution then!
That said... I am just a mom of a two year old... I am basing MY advice to you on what my mom did with me. I hope it helps!
-M.