I get a lot of emails about how one should approach Silverlight and whether they should hold off until the control/layout frameworks are feature complete.
My answer is simple, focus on what you have today as it will be something in which if you invest now will aide you once the framework(s) / future features hit.
I say this from experience, as when I was first given access to Adobe Flex many years ago, it was without a Debugger, No Editor and the framework was being pieced together as I was shown. It was admittedly frustrating at first, but It helped me understand how the technology was starting to take form, it was because of this that I understood how the framework inside Adobe Flex intersects with various other pieces / API's found within the technology.
This is about prototyping, not project building per say. If you can put together a Silverlight piece that does nothing but make round circles bounce off one another, then this is the absolute right attack posture for Silverlight.
If you walk away from a Silverlight presentation and immediately want to build your next RIA and have no or little experience with doing so, chances are you will fail. I say this as despite both Microsoft and Adobe making really strong aggressive advancements in producing RIA, there is still a mindset needed to be undertaken. There are still limitations throughout and it's about understanding RIA first and foremost. It's about playing with the technology physics and getting a feel on how it can assemble and most important of all, it's about knowing the tools you are about to invest a lot of money and time into.
Producing RIA can be fun, but start of with basic prototypes and later the projects will come more naturally.
If you have prototypes, let me know as I want to compile a list of them to show folks both internally and externally.