Librarians are agog about Web 2.0 and this is a double-edged sword. Yes, we should embrace these tools for what they are worth, but that requires knowing what they are worth. Try everything, but be a skeptic. In other words - be a skeptic, but try everything. (Put the emphasis wherever you like.)
Don't like Twitter? That's fine, but find out about it in case someone asks you how it works or whether your organization should be using it. The same goes for Facebook and the like. Blogs are a technology that have finally been seen as independent of the content they were first used to communicate (i.e. rants). "Blog" is no longer a loaded term that sends people into fits. I think we are in a similar transition with Twitter, and it takes longer in some communities of users than in others. Twitter has enormous potential, especially for use in conferences, but we will have to get past the initial enthusiasm and opposition, listen to the skeptics, and then all sit down together to say, "Yes, this is cool, now what?"
Flying solo? Do not take it upon yourself to single-handedly convert your organization into a Twittering mass or to set up a Facebook presence without a clear goal in mind and a plan to sustain your page's activity. What you should take upon yourself is the responsibility of knowing that these tools are considered "the new books" by some - a way of transmitting information, so by all means the librarian should be knowledgeable about them.
The best way to be a resource to your organization is to know your organization, know these tools, and then be able to explain all sides of the application of these tools to your organization's mission. In our case, I am drafting a proposal for using Twitter heavily at our next annual conference but I will be sure to include all the potential disadvantages, such as how to appropriately launch this with our rural audiences for whom broadband access and mobile devices are not as ubiquitous as they are in DC (and how to establish Twitter etiquette in conference sessions).
Remember, don't use a Web 2.0 tool if it's not the best tool for the job. Also, make sure all your social networking tools are fully accessible. See the Environmental Protection Agency (EPA)'s white paper on this topic for model policies.