Here is a Flash Merging example taken with an SB-800 Nikon flash triggered off camera. Four images were taken with the flash held in a different position for each image. I loaded 16-bit tiff’s into Photomatix with the “Exposure Blending” option and blended using the “Highlights and Shadows – Intensive” choice. Its good to play around with all the Photomatix choices and see what you like the best. I even decided to go back and eliminate an image and try a combination of just 3. After I saved the final blended image, I followed with some cloning of the grayed reflections in Photoshop then added curves and color saturation.
You can see some more examples of flash merging in the Strobist group on flickr: HERE