There are now at least three 100-taka note varieties dated 2009. One is signed by Governor Salehuddin Ahmed, and the other two are signed by Governor Atiur Rahman, but the signatures are slightly different (see below).
In addition to the signature change, the text on the back of the note has changed slightly, too. The text on the first note reads Bangabandhu Bridge (named after Sheikh Mujibar Rahman whose official title was Bangabandhu), and the new one reads Jamuna Bridge (named after the river it spans).
Courtesy of Jean-Michel Engels and Nazir Rahemtulla.