Instant messaging is Thing 11. Our city blocks anything and everything for instant messaging, both for staff and public computing. I don't blame them at all because (admittedly, a few years ago) when my daughter had an IM account with AOL, she was constantly getting viruses on her computer. We banned her from using it after re-installing the operating system four or five times.
So, if I decide to try instant messaging, it will have to be at home on my personal laptop. And until I find evidence of it being safer now than it was before, not sure I will compromise security on my laptop.
Last but not least is the usefulness for my library. We are unable to use it and the patrons are unable to use it, and honestly I don't know how popular it is anymore. I usually follow what my kids are doing to find out what is "in", and they are no longer IMing.