Adobe is currently showing some folks how to go from Adobe Illustrator to Adobe FLEX in terms of workflow. This is a positive step for them as they are beginning to catch on that FLEX's limitations aren't in the language, but the actual development lifecycle itself.
That being said, Ryan Stewart of Universal Desktop fame and someone whom I meet with when I was last in Seattle, stated that despite their best efforts – Microsoft – appear to have a headstart in this space.
Now we are looking at Illustrator and Sho is going to demo the work they've done getting Flex and Illustrator to talk to each other. He has the skeleton of a Flex application, and a matching skin in Illustrator. By breaking the Illustrator files into symbols and labeling them then exporting that as a SWF, you can bring it into Flex. To get the skin to display, you point CSS assets at the exported SWF file and the application skins automatically.
It was a good demo, but I still think Microsoft has them beat with Blend. The fact that Blend is a tool made specifically for Interaction Design is a huge jump in getting designers and developers to work together. It may take a bit to get that workflow down, but I think Blend has a big headstart in getting that part of the market.
This is some good old fashion honest praise and Ryan is keeping a level head lately about both brands. It supports a theory of mine that the RIA space isn't going to be decided on just "output" or "x-platform" prowess, it will mostly be decided on the tools that get people to this end point.
It's great that Adobe are warming up to the idea of bridging the gaps between Flex Builder and their respective design tools and can only wait and see what the end results end up like.
Remember: It's not just about the destination; it's also about the journey