SilverLight means many things to many people, it's early days yet, and while there are others doing what they can to scare the living crap out of you on it being a Flash Killer.
It's not, its got more reasons for existence other than being alive for the sake of Flash. You'll start seeing a lot of statistics and so called experts on what it can do vs can't (just assume for a second they are wrong, how does this change your perceptions and go with that thought some more).
What we can tell you now is this, SilverLight is going to allow a software vendors and web designers/developers around the world a new medium to distribute there offerings, companies whom are already making billions of dollars by simply focusing on Microsoft technology offerings are going to also use it in innovative ways.
Distribution is what Microsoft does well, it's why we have Internet Explorer out there, Windows is a house hold name and so on, we aren't new to it's concept and don't be fooled into thinking that SilverLight is just some lazy idea were floating out there into the interweb.
What about Flash? it's a great product - we - use it ourselves, so don't assume we are going to kill it, it has its purpose in life and so does SilverLight.
Enjoy the freedom of having yet another distribution channel and take some time out to atleast try it when it's made available.
Fear, Uncertainties and Doom is just a way to keep scared folks in line, don't be a sheep, make your own choices and decisions about what's good for you.
Keep moving forward.