Here's a brief tutorial that shows one way to use Photoshop (CS2 and newer) to create a high dynamic range photo from multiple exposures.
http://i.gizmodo.com/5168454/how-to-create-stunningly-realistic-high-dynamic-range-photographs
http://i.gizmodo.com/5168454/how-to-create-stunningly-realistic-high-dynamic-range-photographs