As an early adopter of Silverlight etc. the one phrase that grates me each time I hear or read it is "Silverlight, Microsoft’s Flash killer".
And why does it so bother me? Well in my mind it's not a matter of one technology killing the other! As with most technologies, I believe that they'll quite happily live side by side, some people favouring one, some the other.
At least for the foreseeable future, it's not even a matter of who's got the bigger feature set etc., the hard reality, like it or not, is that corporate enterprise type of companies favours Microsoft technologies just like they lean towards Microsoft over open source solutions. While the smaller more fast moving Web 2.0 type companies favour technologies like Ruby on Rails, Flash/Flex and often use open source software.
I recently read a very interesting blog post called Post Microsoft MIX 2008 Thoughts, it's by a Flex/Flash developer called Jesse Warden and it gives an interesting insight into how Silverlight is probably viewed by many in the Adobe Flash/Flex camp.
The post is well written and fairly objective (not much of the MS bashing you might expect from a Flex/Flash developer), it covers his impressions of MIX 2008 and especially the Silverlight related topics that were demoed there. One thing that has stuck in my mind after reading it is how he felt frustrated over the "oohs" and "aahs" of the audience, over things now possible with Silverlight 2 but which according to him have been easily achieved with Flex and Flash for quite some time.
That exact type of thing however is one of the main reasons, which makes me believe that the feature set of the technologies play a lesser role than most may think.
Most people developing in the .Net space, who are often mainly focused on corporate enterprise type applications, just simply don't know anything about what is or isn't possible with technologies like Flex/Flash.
If we lived in a perfect world, we would all live and play together, .Net developers and architects with experience in building large scale enterprise applications, would be bringing their skills end experiences to the table. While the often more UX focused Flex and Flash developers would be bringing their expertise in building visually compelling and well functioning user interfaces along and together we'd be creating truly great User Experiences for the end users.
One can but dream ;)