It's all a bit tentative at the moment, but Keira Knightley is said to be lined up for a new film of My Fair Lady, currently being produced by Duncan Kenworthy and theatrical empresario Cameron Mackintosh.
The story centres on lower class, Cock-er-ney flower girl Eliza Doolittle (Knightley, it is hoped) who is taught to speak and act properly by stuffy linguistics expert Professor Henry Higgins.
The film's being called an "update", but it's still going to be set in 1912 and will use the original score. The "update" will involve going back to George Bernard Shaw's play Pygmalion, on which the musical is based, in order to "dramatise the emotional highs and lows of [Eliza] Doolittle as she undergoes the ultimate metamorphosis under the tutelage of Professor Henry Higgins". There's also talk of a more "realistic" context for the story, using real locations rather than soundstages, and Mackintosh also drew a parallel between Doolittle's transformation and current celebrity culture.
There are no further details on the project yet, but we'll be keeping an eye on this one. And in the meantime, the upcoming Edge of Love shows that Knightley can do accents (in that case, Welsh) and sing, so check that out to form a better opinion of her chances as the new Audrey Hepburn, who last played the role onscreen.