Nope -- they've required that the past few years.
They ask "How well do we know you now?" -- I usually have my clients keep it short and sweet and -- depending on what happens in their interview -- only detail out something they wish they had answered more clearly or didn't get to discuss in their interview. HBS views it as a way to let the candidates have "the last word." I personally do not think it's a make or break thing.
Narenn
I saw this section
"Post-Interview Reflection" on HBS's website today, which requires candidates to submit feedback of the interview within 24 hours of the interview. Is it a new requirement that HBS has introduced from this year?