First Michael Trucco, then Summer Glau, then Wil Wheaton, now Katee Sackhoff:
http://www.usatoday.com/life/television/news/2009-11-02-bigbang02_ST_N.htm
The story gives spoilers on the context of her role in the episode (I don't mind reading spoilers on sitcoms myself, but your opinion may differ). But it sounds like she's only in the ep for one scene. Still, figured I'd mention it in case anyone here was interested.
http://www.usatoday.com/life/television/news/2009-11-02-bigbang02_ST_N.htm
Her appearance is the latest of several geek-fantasy guests on Big Bang, whose ratings are up more than 40% in Season 3. The comedy draws nearly 14 million viewers an episode and is a top series among young adults.
The guest shot comes after a year's worth of lobbying by co-creator and Battlestar fan Chuck Lorre, who originally envisioned her as the object of fanboy desire in last season's "The Terminator Decoupling." Sackhoff passed, and The Sarah Connor Chronicles' Summer Glau stepped in as the sci-fi starlet trapped on a train as Wolowitz and his friends try to woo her.
Lorre got another shot when Sackhoff visited the Two and a Half Men set with close friend and fellow Battlestar alumna Tricia Helfer. He pitched another scenario in which she'd play herself, and this time she agreed.
The story gives spoilers on the context of her role in the episode (I don't mind reading spoilers on sitcoms myself, but your opinion may differ). But it sounds like she's only in the ep for one scene. Still, figured I'd mention it in case anyone here was interested.