im not so sure how you would get that info on the server side unless you passed it in with a call to a meteor method. In that case you could get the path from the controller object to pass along.
To just query that info on the server at any point in time. I dont know of a way to do that.
I will read through the iron:router documentation tho and look further. I also use iron:router so I am curious now. If i find out anything I will post it here.