A RADAR controller at SDF described near loss of separation event when they failed to insure correct routing on initial contact. Corrective turns were issued after being alerted by an adjacent controller.

Narrative

Tower cleared MD11 for takeoff on Runway 17R at a heading of 190 (normal procedure). Pilot did not read back heading given. When the MD11 checked in with departure; he reported being on Runway heading. I missed that. At the same time; a CRJ7 was cleared off of Runway 17L; on runway heading. I climbed both aircraft to 10;000 FT; assuming that the MD11 was turning to a 190 heading. Approximately 4 miles off the departure end; when the 2 departures appeared to be on parallel tracks; I turned the CRJ east to join his course then the MD11 west to join his course. The eastbound turn for the CRJ put it in the path of an inbound B737 that was being worked by another controller. That controller alerted me to the situation and descended and turned the B737 east and I turned the CRJ north. The CRJ reported the B737 insight and was subsequently told to maintain visual separation. The MD11 pilot did not read back the heading when he was cleared for takeoff. Had the pilot read back the heading along with his takeoff clearance; the tower controller may have been able to correct him. Also; had I heard the MD11 pilot's initial call on runway heading; I would have turned him immediately to the assigned 190 heading. An RNAV standard instrument departure (SID) procedure has been in the works for several months but has yet to be developed. Such a 'tool' may have had the MD11 pilot in a westbound turn on his own; thus negating the eastbound turn of the CRJ toward the B737. At the time; I did have 3 or 4 other aircraft on frequency.