Unfortunately the Legendsong has never been released in the US, and sadly I don't think they're planning to release it at any point soon. And I have absolutely no idea if anything's been discussed, but I'm really hoping they'll release them in the US for when Darkbane comes out - one can hope, right? [act]crosses fingers[/act]
For a complete list of IC's books and short stories, including current availability, please check out
this booklist - to the best of my knowledge, the information is correct and up-to-date, but please let me know if there are any errors. :)
Oh, and please note there's a couple of short stories I've heard rumours about, but never managed to track down, so I'll add them if I can find proof of their existence. ;) (For interest's sake, they're called Bear Flower (or Bearflower) and Archimboldo's - if anyone can find out anything about them, I'd love to know!)