Steve Jackson Games has been making GURPS sourcebooks for the Traveller system since 1998. That will be coming to an end on December 31st of this year. This means that SJG will no longer be making or selling those products. If you're a fan of the GURPS Traveller books, but you've not gotten all the books you wanted yet, you've got 5 months to pick the last ones up if you want to get them right from Steve Jackson.
Anything that's current available will only continue to be so while there is stock in the warehouse. There won't be any more print runs between now and the end of the year. Loren Wiseman, Line Editor for Steve Jackson Games, has said, “All good things must come to an end. After over 50 products, not counting T-shirts and the like, working with Traveller has been more fun than human beings should be allowed to have, and we at Steve Jackson Games would like to thank Marc Miller and everyone else connected with Traveller for allowing us to play with our version of the game for 17 years. Thanks!”