A new Hollywood Reporter article features a bit of information about SHREK THE THIRD, which is...in case you couldn't figure it out from that title...the third installment in SHREK theatrical franchise.
The article says that (alongside returning leads Mike Meyers, Cameron Diaz, Eddie Murphy, and Antonio Banderas) Ian McShane will voice Captain Hook, Eric Idle will perform Merlin (which I believe had been announced previously), and Amy Sedaris (STRANGERS WITH CANDY) joins the cast as Cinderella.
How does Cinderella show up? HR says this:
The next installment of the smelly ogre's saga, set for release next year, will star an elite, ninja-like strike force of fairy tale princesses voiced by Amy Sedaris as Cinderella, Amy Poehler as Snow White, Maya Rudolph as Rapunzel and Cheri Oteri as Sleeping Beauty.
Organized by Princess Fiona, the ladies underground resistance movement fends off a coup d'etat by Prince Charming (Rupert Everett) in the land of Far, Far Away.