Hideo Kojima has teasted an upcoming announcement on Twitter (our favorite source of news!), according to Andriasang who translated the tweet.
""Typhoon 4. It looks like it won't have an effect on the weekend. Thank goodness! However, my health is bad. Prior to TGS, we'll have a big announcement on Saturday or Sunday, so I must recover," the tweet mysteriously read. Kojima then clarified that it had nothing to do with Zone of the Enders 3, saying that "ZOE3 and so forth - it's not that big an announcement. However, I think you will be happy."
Check out the original tweets, in the original Japanese, right here and here.