Rails - Jul 2006 - 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 ideas?

--
Brad Ediger