It looks like Daniel Craig may be Hollywood's pick to play Mikael Blomkvist in The Girl with the Dragon Tattoo US version.

With the Lisbeth Salander character from the book described as weighing less than 90 lbs and standing 4 ft 11 inches, I cannot think of well known Hollywood actress who could play her. Christina Ricci comes to mind but she is thirty or so and seems too old for the part. Salander from the books looks like a teenager.