For now, anyways. I assume the shuttle to fly the additional mission will be Atlantis, as she'll be the "ready" shuttle for what was projected to be the last one.
http://www.washingtonpost.com/wp-dyn/co ... sec-nationPanel approves compromise plan to save space jobs and add shuttle missionQuote:
But the three-year NASA spending plan passed by the committee adds a $1 billion shuttle mission to the international space station for next summer or fall and leaves contracts, equipment and personnel in place in case other flights are needed.
Still has to pass the House, but the Admin is supporting it and TPTB want the potential cuts in NASA personnel off the table in places like Florida before voters show up at the polls in November. Might end up being a situation similar to that with the USS John F. Kennedy during the last years of her active service: shuttles and their infrastructure will be kept ready, but no more actual flights beyond the additional 2011 one.