I used the google translator on Nintendo.jp:
May 22nd in the afternoon, the [sumabura] fist does [riniyuaruopun]
Not that I understand that, but it links to the Smash Bros. Page. sooo..... 'In the Afternoon'.
It's 4:00 AM over there right now. Noon in Japan is 11:00 PM Eastern, 8:00 PM Pacific.
Also, here are my predictions for this announcement: Gameplay footage shown, confirming returning characters from SSBM (at least the 14 unlocked from the top of SSBM, if not more), Sonic the Hedgehog as a big 'reveal', kinda like Snake was last year around this time, Miis as playables... and at least five new stages revealed. I can't wait to see the new character renders of Captain Falcon and Bowser, especially.
Note: I hold onto the belief that no characters will be cut, since SSBB is being built from the code for SSBM, so there's no reason characters couldn't make it in. Even Ice Climbers.