"Grey's Anatomy" to be wiped out - by cast member?

Glitterati Gossip reports that "Grey's Anatomy" will add Chyler Leigh to the cast for 13 episodes, after her bit hitting on McDreamy in a bar in the season finale. But the 25-year-old Leigh has already been on nine different series, most of which were quickly canceled. Could she be the greatest TV jinx since the late Robert Urich? ... In unrelated hottie casting news, TV Guide reports that "Smallville" will add 22-year-old Canadian Laura Vandervoort as Supergirl this season.