Why, you might wonder, does the Oscar-winning director feel the need to add a touch of the feminine to J.R.R. Tolkien's "blokes of all sizes go on an adventure without girls getting in the way" classic?
Because he bloody well wants to, that's why. And I'm inclined to let him, given how well the changes he made to The Lord of the Rings turned out. Sure, The Hobbit might be a boys' adventure tale, but a Hobbit movie needs to attract more than boys—and this wouldn't be the first time that Jackson has diverged from the text to make the films more universal: The Aragorn-Arwen romance thread that ran throughout the Lord of the Rings trilogy was mostly a Jackson invention, and it went a long way toward helping those films reach as wide an audience as possible.
To that end, Jackson has already brought Cate Blanchett's Galadriel back for the two-part prequel, even though she's nowhere in Tolkien's Hobbit, and he's looking for another actress to head to Middle-earth. A casting sheet reveals the role to be:
[ITARIL] FEMALE, A WOODLAND ELF, this character is one the Silvan Elves. The Silvan Elves are seen as more earthy and practical. Shorter than other elves, she is still quick and lithe and physically adept, being able to fight with both sword and bow. Showing promise as a fighter at a young age, ITARIL was chosen to train to become part of the Woodland King's Guard. This is the only life she has ever expected to live, until she meets and secretly falls in love with a young ELF LORD. This role will require a wig and contact lenses to be worn. Some prosthetic make-up may also be required. LEAD. AGE: 17-27. ACCENT - STANDARD R.P.
Saoirse Ronan, who worked with Jackson on The Lovely Bones, has been mentioned in conjunction with The Hobbit—and perhaps this is the role she'd play—but nothing is set in stone.
(via Bleeding Cool)