I've been wondering about this, but I can't find any sources one way or the other:
Was the space shuttle equipped with a stick shaker and\or other stall warning system?
The shuttle was not built with this capability. NASA AMES had a project MIDAS intended to improve the shuttle's cockpit information display and management. In its list of problems to address:
Finally, there is no warning or guidance/autopilot limiting when approaching a stall on entry.