Access session from observer?

I am writing a logger observer that provides an audit trail for most
events that touch my AR models. I am using the acts_as_authenticated
plugin for user login. What would be the best way to expose the current
user to my observer?

I’m not looking to violate MVC here (well, maybe a little – though a
logger seems more like a controller than a model to me). I just want the
logger to be as low-touch as possible wrt my other models. Any clever

Brad E.