FYI: Last year, the "end of april" message was delayed and was sent out on May 6, 2006. The representative from AdCom wrote at the time:
Date: May 6, 2005
Thank you for your patience with the delay in this "end of April" update. The Admissions Board is focusing this week on third round applications, and continues to interview both Round 3 and wait list candidates. The Round 3 notification date is May 11.
For the record, email communication on the wait list LAST year was:
Apr 7 (telling round 2 wait list candidates they are on the list)
May 6 (see above)
May 31 (telling us updates will be send out on Fridays and that by late june the WL will be small)
Early June, was when I recall hearing the first flurry of admit/ding notifications
June 16 (to tell us the procedure for updating contact info has changed)
June 17 (when I got a ding. Many others heard then too.)
Incidentally, when the WL decision came last year, it was an email from the ApplyYourself site with the subject "HBS Decision Available Online". You go online and instead of the WL letter, you get your ding or your admit.
Hope that helps someone. Honestly there is not much we can do. HBS is a great institution and it is an honor to be on the WL: just ask anyone who was dinged outright. We should all take it as a compliment, but make alternative plans just in case. I did a lot of research last year on this by digging into past threads and it seems that year to year the chances of getting off the WL are very very low.
Warm regards.