Harlequin goes YA.
Over at Dear Author:
I emailed Harlequin and was told that Harlequin appears to be entering the YA market and are “seeking YA submissions, notably in the areas of paranormal, fantasy/sci-fi, relationship/romance and social issues.”
According to one of the commenters, Harlequin actually entered the YA market last year with their Kimani TRU imprint. Check out their guidelines -- pretty specific about what they're looking for, huh?
(First link via Urban Fantasy Land)