It would be real useful to be able to have more than one Tweet button on certain content type. For content types that usually ends up being several screen sizes long I would like to have the default at the top, but then a second after the content. My gut tells me that most users wont scroll back to the top just to tweet, but if there is a button right where they finish reading the likelihood is much higher they will use it.
Preferable it should be possible to use different button styles, such as vertical at the top and horizontal at the bottom.
Whenis implemented my guess is this should not be difficult to implement as well.