It's very cool, but is in danger of being killed since Adobe bought Macromedia as there's now overlap between FW and Illustrator. And Adobe is generally pretty evil.
Adobe had image-ready to compete with fireworks. Upon acquiring the Macromedia products, they canceled the image-ready line. Illustrator is a vector editing/illustration suite. Fireworks is a web graphics suite. No need to worry, there is no major overlap (or at least not enough to warrant canceling a popular software title).
http://labs.adobe.com/technologies/fireworkscs4/