Here's another theory involving the update icons.
http://www.smashbros.com/en_us/list/old_list09.html
Now look at where the update about E for All is placed.
Next, look at this page:
http://www.multiverseworks.com/smashicon2b.php
As you can see, like I said earlier, between Sonic's video update and his special moves are two icons not available, meaning, at these two points updates were supposed to be made which didn't have icons. However, we can see from the list that between Sonic's video update and his special moves update there is just one icon-less update, the Nintendo Fall 2007 conference video.
Also, between Sonic's special moves and the taking snapshots update, there supposed to be the E for All update, yet on the icons page, the snapshots update follows the special moves update directly. Instead, this undefined icon has been pushed before the special moves icon.
So, this made me think that Nintendo had planned on putting the E for All update the day after Sonic's confirmation.