@ Hemantuec: I did send them an update on 13th/14th Jan. I have recently got a promotion at work(in a relatively short period of time), so I sent them a letter (scanned copy through email and a hard copy through DHL). I talked about my promotion and also emphasized that Kellogg was my first choice school.
Apart from this I have had no interaction with any adcom member (except my interview ofcourse). I did not even know that something like a waitlist manager existed before I started browsing through these forums.