Not sure if they have new birthday buttons, but I know that they are adding more types. Can't remember what exactly, except that the Honorary Citizen button will be changed to a button that says "I'm Celebrating" and then a place to write what you are celebrating.
There are all sorts of new buttons, but they have to get rid of the last of the '08 stock before they get all the new ones in, so I can't say for sure what will be available on any given day. The celebration buttons ARE available now, but there is nowhere to write on them.
"Remember 'Old Yeller'? We shot the dog." - Roy E. Disney