Pretty sure VxWorks is still used today for a lot of spacecraft; Curiosity[^1] and at least at one point the SpaceX Dragon capsule[^2] it looks like.

^1: http://www.windriver.com/announces/curiosity/ ^2: http://www.spacex.com/sites/spacex/files/pdf/DragonLabFactSh...

Yes, lots of spacecraft use traditional RTOSes like VxWorks, RTEMS, ThreadX, uCos, etc. Keep in mind that there are many computers on a large spacecraft - attitude control, command and data handling, instruments, and other microcontrollers.