Sony Films plans to launch its marketing campaign for Columbia's Spider-Man 3 with a high-definition, 2 1/2-minute trailer for the movie set to be posted for downloading from MTV's website at 9:00 p.m. tonight (Thursday). An hour later, the trailer is scheduled to be broadcast on CBS after CSI: Crime Scene Investigation. It is also due to be shown prior to South Park on Comedy Central and before Real World/Road Rules Challenge on MTV. In addition, the trailer will be unveiled in theaters beginning on Friday, nearly six months before the official opening of the movie on May 4.