I was a little unsettled when I saw that Facebook was part of the 23Things programme. I'm not really a fan of Facebook, but I do have an account, which I set up for the purposes of keeping informed about the activities of the Cambridge University Ballet Club, of which I'm a member. I use it for sporadic social communication, and probably check my page about twice a week on average. I am also tagged in quite a number of photos, some of which are of me dancing. I'm definitely not saying there's anything on Facebook that I'm ashamed of, but I did balk a little at the idea of colleagues and professional peers seeing me in a leotard and tights!
Because I use Facebook as a social utility I have hitherto been fairly skeptical about the idea of libraries on Facebook. However, as Lyn rightly points out, "it could be argued that libraries should promote their services where their
users are and if that is on Facebook then the library needs to be there". I've had a look at some existing library pages on Facebook and I think the ones that work are those that really exploit the functionality of Facebook as a tool for communication and are truly dynamic. The content of others is much more static and passive, and in my opinion better suited to a bespoke website, where the information can be presented to best possible effect, rather than squeezed into the Facebook template.
I suppose what I'm saying is that I don't think every library should be on Facebook for the sake of being on Facebook. And that if a library is going to use Facebook it should use it well. Some libraries show us that Facebook can be a great tool for libraries, and it would be great if all libraries were able to use such active and dynamic ways of communicating and interacting with their users; but if you haven't got the time to manage or support for the idea of managing a Facebook account, it's not a disaster. Other ways of communicating (websites, blogs, emails, flyers, noticeboards) are still viable!