Addison Shepherd assists a very pregnant Dr. Bailey.

A photo from the May 1, 2008 episode of Grey's Anatomy, entitled "Piece of My Heart." Dr. Addison Montgomery (Kate Walsh) is back at Seattle Grace and talking to her old friend, Callie Torres (Sara Ramirez)!

Not a real romantic reunion, of course (and thankfully) - but Addison and Derek are back together on Grey's Anatomy at least for one week, sparring over surgery.

Dr. Addison Montgomery Shepherd and Dr. Miranda Bailey converse.

Richard, Addison and Cristina see that the cancer has spread.

Addison's scrubs may be the object of ridicule, but there's no doubt that Mrs. McDreamy knows her stuff.

Assigned to a particularly odd case.

Seen here, Addison Shepherd poses for a picture

Addison rolls to L.A.

Meredith, Addison and Derek bid farewell to Doc.

In this photo from "Piece of My Heart," Dr. Derek Shepherd (Patrick Dempsey) may be wishing he had taken the stairs about now. Lots of women he likes in there!

Addison Shepherd looks on, concerned.