They are the Ditty Bops a recent find of mine (although I also know that they've been posted about in a few other blogs) who certainly wouldn't be out of place on the Back To The Future with their very retro jazzy/folky sound with more then a hint of swing style, although their sound certainly doesn't sound stale in a similar way to the Pipettes sounding retro but still incredibly fresh heres their about me section on their MySpace "Amanda and Abby are from California. They started their band almost three years ago. Abby plays guitar and Amanda plays mandolin. They sing in harmony and are joined by their band of boys who play violin, upright bass, lap steel, and piano".Dude just listen to the music (you can find more on their MySpace page).
Ditty Bops-Angel With An Attitude
Moon Over The Freeway-Ditty Bops