This weekend I read a blog by a well known person in Flex community and found a very interesting phrase there:"If you take a careful look at Catalyst it flips the % of design and development work within an app. Where development was 80% of an app, it is now 20% and Design/Interaction was 20% is now 80%".

Sorry for taking it out of context, but I think it will be taken out of context or even becomes a mantra for new development process the same way UML 10 years ago was suppose to produce 80% of the application out of structured requirements. I am certain that this interpretation was not intention of the original blog author.

I would suggest that 80% - 20% separation has to be clarified as it might be used by some as Adobe's recommendation of budget/time allocation and it could be problematic for the current state of the industry.

Less generalized statement IMHO would be this:
In order for applications to be successful in consumer / occasional user market you will need to increase your typical “functionality based” budget few times for usability, design and testing. You will also need to keep lid on features in order to achieve usability staying within budget constrains.

Applications targeting mobile devices and occasional users on conventional ones are definitely a growing trend that Flash platform is best positioned to take over. Enterprise and niche application will still be out of reach of UX due to budget / features constrains – so the following notes might not apply.

I agree that most of the current design work goes into packaging (opening page(s) and stylesheets) and does not affect the quality of the application. I would argue that cinematic experience is more important than design. For example, in the movie industry films based on beauty rather than the character have higher attrition rates and lower retention.

IMHO, there should be stronger distinction between visual design (how it looks) and "interaction" design (how it does things).

People will adapt to anything that is simple and easy to understand. Current UX wave is driven by people who have taste, which can be acquired over time... even by developers. Time is of essence here - developers just need the same tools and reasonable project deadlines as the rest of the team rather then cram their time toward the end of the project.

In my experience it takes less then 6 month for a developer moved from PC to MAC OSX to “forget” old way of doing things and acquire the same taste for simplicity the designers historically enjoy by using designers products. Adobe developers have long history of using non-Microsoft systems and it is definitely reflected in the way the build applications with or without designers.

At this point any serious Flex developer working on consumer-facing project must go through at least some training in Web Design to the extent that they can modify Photoshop,  Illustrator or Flash files to annotate/fix a design flaw and communicate it properly to the designers. That implies to a large extent that 60-80% of the overall time is still in the development as developers extended their reach into modern UI. It also greatly reduces overall project time and mis-communications.

I certainly hope that Flash Catalyst will be bridging the gap for the rest, but expect mixed results if people would not expose themselves significantly to the other side of the fence.  Finally, as client portion of RIA becomes simple and intuitive, more work needs to be done on the server to prepare and support such predictable and intuitive behavior.

I lived through few projects of complete picture perfect designs made upfront. Unfortunately, those static pictures are full of loopholes. Good developers are just as good as good designers in interactivity and much better with data models and overall process. In the end, negligible percentage of the picture-perfect upfront design is usable and could be counterproductive for the project lifecycle as compared to conventional wireframes as a common ground. Only from common understanding (the more visual the better, but not ONLY visual – you need to make sure it is also in words so you can ensure common understanding, provide comments and establish two-way process) you can start real team work on your next RIA project.