I just got back from the airport, and I saw a Delta Airlines MD88 make an emergency landing.
Delta Flight 441 was on its way from Toronto to Memphis with a stopover in Atlanta. It left on time at 8:30 PM Toronto time, departing on Runway 24R, and returned about 5 minutes later, on 24L.
I was listening on my scanner, and the pilot reported smoke, although I'm not sure where the smoke was located, whether it was inside or outside the aircraft, since I didn't see it up close while it was landing - I was near 24R, but I could see it made a real sharp turn on final approach, and it landed safely. Before it landed, all air traffic around 24L was cleared away from the area as the air traffic controller told a United Airlines aircraft near 24L that "An emergency is in progress". All aircraft went on 24R while this was going on. Afterwards, the controller asked the pilot if he would like to evacuate the aircraft, but the pilot said that it would not be necessary unless the emergency crews on the ground noticed smoke. I just checked Delta Airlines' website, and it shows that the flight is at the gate, and is expected to depart Toronto at 10:00 PM. I'll try to find out more information later.