Bust out your Blackberries and Fire-up your Sidekicks ... we've got Gossip Girl News. Blake Lively (could she be a Stardoll soon herself ?? I wonder) has a new cast-mate ... who will be playing her frenemy Georgina Sparks. Yes ... the Sparks will be flying.

Michelle Trachtenberg has joined the cast of Gossip Girl. Buffy's Little Sister is back ... will she be slaying Prep School Upper East Siders.