In Haywire, Gina Carano plays an assassin whose employers decide to terminate her. An extremely original plot? Perhaps not, but it still looks like one to watch out for, based on the trailer (below).
Incidentally, Carano is a mixed martial artist and used to be a Gladiator.
There seems to be a mini-spate of awesome action films starring women in recent years (Hanna and Salt spring to mind). Hollywood Reporter notes that the plot is also startlingly similar to the forthcoming Colombiana.
Here are the trailers for the two movies: