I think Silverlight would have been a great idea 4 or 5 years ago. I would have been a true killer app for asp.net/c#. However, the Achilles heel of all these

I think Silverlight would have been a great idea 4 or 5 years ago. I would have been a true killer app for asp.net/c#. However, the Achilles heel of all these applications is that they are not google friendly. Meaning they can't be indexed for search. This is fine if you use Silverlight/Flash/Flex/"Acronym of choice here" for a portion of your site (calculator, graphing, media player). However, the learning curve for these technologies is always steep. Now not only do I have to know php/asp.net/etc but I also have to know some kind of rich client application. I see the sweet spot as media player for your site. Take http://www.pandora.com/ http://www.pandora.com/ for example. This is a good way to use these rich client frameworks. That being said, when I can't copy and paste text from these application, it really limits their usefulness. HTML/CSS/JavaScript is a pretty good stack. There will have to be something that really compels me to use them before I'll divert the resources of my shop to learn/adopt/deploy them.