Although it was supposed to launch with the new Galaxy S8 flagships, we now hear that the Bixby voice control features will not roll out in the US at the same time as the new Galaxy handsets, being scheduled to arrive "later this Spring" instead.
http://www.notebookcheck.net/Samsung-Galaxy-S8-to-launch-without-Bixby-s-voice-support.212832.0.html