There is no date announced yet for RD notification; watch
Ben's and
Matt's blogs for the official news.
In the past couple years on the date specified, it was possible to login to
https://decisions.mit.edu (which currently just redirects to the Admissions website, but where in past years you signed in using the same account and password used for your MyMIT) to view your decision. Decisions will always also be sent through the mails. The blog entries announcing the decision date will have instructions about this process.
Last year Ben announced on March 12th that decisions would be released on March 17th, so expect a few days' notice anyway.
(And yes, someone has
already asked this.
)