Our team lead has an odd aversion to using IM, which extends to distrust of any electronic messaging beyond email. However I really feel a persistent chat room would be a big help for the team.
Another thing I like about using a room is the chance to use Hubot (http://hubot.github.com/). It makes for some fun and can also be extended to actually do useful stuff.
If your team as an aversion to IM try to entice them with a room is better because it's not one to one and everyone can see and answer questions and it facilitates group discussion easily and it's asynchronous so it gets out of your way.
If skype had threaded chat conversations, it would be much more manageable. Until then, I miss gmail... :)
Use the right tool for the job.