I am so sick of hearing that question! Sick of it I tell you. Everytime I see someone around the university that's what they ask me. Now I'm hoping it is because my supervisor and half our lab up and moved to the US and there is only me and another grad student left behind to fend for ourselves and everyone is suprised I didn't go. However, I also wonder whether people ask me this because they think I should be done by now. Perhaps someone should notify my committee of this little tid bit of info. At my last meeting a couple months ago one of my committee members made the comment of, "Oh you haven't been here that long" to which I replied, "It's been long enough". That same committee member suggested, in a moment of speaking before thinking, that I perhaps make a knockout mouse. Oh yes, hang on a sec while I sign up for the 15 year PhD!
Perhaps I should send out a departmental email stating that yes I'M STILL HERE! And stop asking me!