The Mirror reports that Blake Lively and Gossip Girl costume desginger Eric Daman attended Victoria's spring 2010 presentation in New York last month: "Blake attended the unveiling of Victoria's new collection in New York last month, alongside the series' stylist Eric Damen. The trio started chatting and Victoria revealed she was a huge fan of the show. From here, Blake pleaded with her to guest star in an episode and ran the idea past producers." If you recall, Blake and Leighton have worn VB designs both on the show and off. "Blake and co-star Leighton Meester are fans of Victoria's designs, and have both worn her dresses."
What kind of role she will tackle still remains a mystery but a few possibilities had been thrown. "She isn't an actress and wanted her role to be very tongue-in-cheek," a source claimed. "And an idea for her to play Brit actor Ed Westwick's long-lost mother was quickly vetoed. Victoria joked that she'd rather play his ex-love interest!" I've also heard rumors that she will play herself.
source: ACE Showbiz