'Will & Grace' star Megan Mullally set to guest star on 'Up All Night.' Mullally will play Shayna Mund, a rival talk show host to Maya Rudolph's character Ava, for one episode. Shayna used to be Ava's protege, but now she'll stop at nothing to beat her, even if that means stealing Ava's show ideas.

http://www.aoltv.com/2011/11/14/kelsey-grammer-returning-to-30-rock/