Sorry, y'all, but this totally pings my fannish squeedar so I have to share:
Michael Dorn (aka Worf from Star Trek: TNG and ST: DS9)
has been cast in a recurring role as Beckett's psychiatrist on Castle this season. This means there'll be a mini-DS9 reunion, as Penny Johnson Jerald, the new captain, had a recurring role as Kassidy Yates. (Also, in Castle's 2nd season, René Echevarria was an executive producer and writer, which he also was on DS9.)
Besides, Michael Dorn is such a lovely, lovely man. And I'm going to end this post now before I start playing the Star Trek version of "Six Degrees of..." and y'all realize how truly pathetic I am. ;-)