Smoke can be seen on the visible satellite image below. The image is from just after 7:00 PM EDT on August 27. The smoke is the lighter grey color across Iowa, Nebraska, Kansas, and parts of Illinois and Missouri. The smoke originated from fires across the western United States. An animated version showing the smoke's movement for about an hour is available as well (1.2MB animated gif)
The following image annotates the above picture to highlight the smoke area. Click the image for a larger version.
Here is the Hazard Mapping System Smoke and Fire Analysis Map near the image time (Click to Enlarge):