The level design and artwork are done simultaneously inside of Fireworks. I have an extension which attaches metadata to objects to use in-game. I also rely on states and pages to correspond to animations and levels respectively. I.e. all of the levels of the game are "compiled" from a single fireworks doc with 20 pages, each page corresponding to a level.
That is great! It's definitely one of the most clever and unique uses I've seen of Fireworks. Hopefully, someone from Adobe is reading so they can recommend it as an article on the Fireworks Developer Center (http://www.adobe.com/devnet/fireworks.edu.html).