As a former waitlister who was accepted, good luck to all of you. I applied R1 3 years ago (has it really been that long?) and was waitlisted the day before the notification date. I was admitted along with the R2 applicants in mid-March.
Just be patient with the process. A waitlist means that you are good enough to make a meaningful contribution to life at Kellogg, but they just want to see how the R2 applicant pool looks before finalizing anything. Further if you have any meaningful updates to tell them, by all means let them know, but don't get in touch just for the sake of getting in touch.
Personally, I only sent one update in late February and that was because I'd been working on a new product for a consumer electronics company. In my application, I'd described my work but not with too much detail. When my company went public with the new product, I wrote to offer more information regarding my contribution.
Good luck to all of you with the process!