From MTV News’ Jennifer Vineyard:

Michelle Trachtenberg was “the key” on “Buffy” — but will she now unlock secrets on “Gossip Girl“? MTV News caught up with the saucy actress on the day it was announced that she’d been cast on the hit CW show for a few episodes in May - sweeps week, yo - which also happened to be during the “Buffy” reunion. Trachtenberg will play Georgina Sparks, who comes fresh off a stint in rehab to torture Serena and Blair. How she put it:

What sort of stuff? Well, try for starters the real reason Serena left town in the first place. And Georgina, as you might recall from the books, knows Chuck from taking his virginity (in the sixth grade), knows the Dutch snowboarding team from hottubbing with them naked, and knows her former fling Nate from rehab. Could that be where she really met Serena as well? This could be great! And remember, this juicy role is something Mischa Barton was rumored to have originally turned down.Trachtenberg starts work on the show this week in New York, and will appear in four of the show’s five episodes for the second season, with her first appearance airing on April 28.