A promotional photo from the May 1, 2008 episode of Grey's Anatomy, entitled "Piece of My Heart." Dr. Addison Montgomery (Kate Walsh) is back and walking alongside Miranda Bailey (Chandra Wilson). What's to come of Addie in this episode?

She's pregnant! Adele!

Derek and Addison... along with her guest.

Old friends treat Adele.

So close!

Private Practice's Naomi and Addison make their way to Seattle Grace to treat Addison's brother Archer.

Mark clearly has something on his mind, while Alex feels a spark between Addison and himself.

Awww, remember when these two were good pals? We'll see them interact again on the Grey's Anatomy episode "If/Then."

A promotional photo from the May 1, 2008 episode of Grey's Anatomy, called "Piece of My Heart." Dr. Addison Montgomery (Kate Walsh) returns and talks with her ex-husband Derek Shepherd (Patrick Dempsey). This one should be good!

Derek, Addison, George and Richard share one of the few happy moments on this traumatic day.

George and Addison help Miranda give birth.

Drs. Grey and Montgomery talk medicine.