I don't know if it's been mentioned anywhere yet, I hope not, but Raymond Benson's website specifically states that his next novel is finished and will be published in November 2005.
I've only read Tomorrow Never Dies by him, but I did enjoy the first Splinter Cell novel. It was very much like a Bond adventure except...well umm without Bond and his characteristics

and it was told in the first-person. Good stuff. Anyway, can't wait for the second one.
Related note.. the games are awesome, although I've yet to play Chaos Theory.