http://www.bigfinishgames.com/games
The developers site doesn't seem to say anything about a new Tex Murphy game. Although that doesn't mean it isn't coming.
EDIT: I just read that announcement from the second post. This is something I definitely will donate toward. I am not sure if it will be a good game or not, but Under a Killing Moon was one of my favorites when I was in High School.
I did try playing Overseer lately, and I couldn't get into it. The controls are completely counterintuitive compared to modern first person games. I hope they adjust their controls accordingly.