So has hell frozen over, then? She said she would never go back.

Olin Returns from Dead on ‘Alias’
LOS ANGELES ( Scarcely an episode of “Alias” has passed this season without Sydney (Jennifer Garner) or one of her colleagues remarking on the death of her mother, Irina Derevko.
Hey, even double-secret CIA agents can be wrong.
ABC confirmed Thursday (April 21) that Lena Olin, who played Irina during the show’s second season and had since resisted creator J.J. Abrams’ entreaties to return, will guest-star in the show’s final two episodes this season. They’re scheduled to air at 10 p.m. ET Wednesday, May 18 (the second of two episodes that night) and May 25 (following the two-hour “Lost” finale).
Reports of Olin’s return have been bubbling for several weeks, but ABC is also offering a few details about how her character will be worked into the show’s story. After finding out she’s alive, Sydney, Jack (Victor Garber) and Nadia (Mia Maestro) will track Irina down and enlist her help in stopping a catastrophe brought on by followers of the mysterious Rambaldi.
Unanswered for now is the question of just how Irina is still alive. Viewers have repeatedly been told that Jack, her former husband, killed her to prevent a hit on their daughter Sydney’s life; that would mean she either survived Jack’s assassination attempt, or he’s not telling all he knows.