Click here to read what Jon has to say on this. I found this part interesting:
Whatever is decided, MLB would prefer the Yankees wait until after the World Series to make the call. While an MLB spokesman said he didn’t think official permission to make the announcement would be granted, the Yankees appear to be shooting for the World Series off-day Friday (though “we won’t rush it,” one Yankees person said). MLB prefers the Yankees wait, but Yankees people ignored MLB’s request not to have a conference call Wednesday with Pena and want to get on with their immensely busy winter.
When you consider how much money the Yankees give MLB, I say “Tell us on Friday” and the heck with what they would prefer (the Yankees did with the announcement).