Denise Richards is heading to '30 Rock.' According to E! Online, the actress will appear in the upcoming sixth season.

"So excited!! I'm going to be doing an episode of #30Rock! one of my favorite shows!!!!!" she tweeted.

James Marsden has also booked a '30 Rock' role. EW reports his role could be recurring, but NBC isn't revealing details. Could he be Liz Lemon's new lover?

Richards and Marsden join previously announced recurring guest star Will Arnett on the upcoming season of '30 Rock.' No premiere date has been given, but best guess is it'll show up on NBC sometime in the winter.

In other casting news ...

In a time when even Paris Hilton publishes her memoirs, it's rare to hear about a celebrity autobiography worth reading. Charles S. Dutton is telling his life story in a book for Random House's Crown Books. Dutton has done a lot of acting and directing for various TV shows, most notably Roc. He won a directing Emmy for The Corner as well as Outstanding Guest Actor Emmys for Without a Trace and The Practice.

What makes Dutton's success story unique is his personal life before he became an actor. When he was seventeen, he was convicted of manslaughter and spent seven years in prison. From Jail to Yale, the working title for the actor's book, will discuss Dutton's criminal history and his education at the Yale School of Drama.

The Threshold DVD has been out for a while now. But for casual fans like myself who liked the show but don't really feel like shelling out forty bucks for the DVD set, this is good news. As Bob mentioned here, Sci-Fi has been airing repeats of the first nine episodes and it was supposed to include the final four installments of the series. No dates were set for those at the time though. Now we have them and they're coming... tonight.

The final four Threshold episodes ("The Crossing," "Outbreak," "Vigilante," and series finale "Alienville") will air in a row starting at 8PM tonight on the Sci-Fi channel. Supposedly, the finale is supposed to be completely ridiculous (in a good way), so I'm looking forward to seeing how things turned out for Dr. Molly Caffrey and the rest of her team.