I've received the following question (in various forms) three times in the past two weeks, so I'm going to take the opportunity to post it and my response (such as it is) here.
"… I read that if Microsoft had supported SVG, this there would have been no need for Silverlight and that Silverlight is just a reinvention of SVG to protect Internet Explorer."
"The blogs say that Silverlight is just SVG reinvented to be owned by Microsoft"
My attempt at a reply usually boils down to something like this…
I never know how to begin to answer questions like this. If Silverlight and SVG were equivalent technologies, this might be a debate that some would benefit from, but I believe they are really quite different, serving different purposes. Silverlight is an emerging technology in the spectrum of .NET tools for developing applications and I think you'll find that the appeal of Silverlight, strong as it is, will be an order of magnitude stronger when we unwrap Silverlight 2 in a few weeks.
I don’t mean to dismiss your question; it is just not what I do; I’m best at helping folks learn and use Silverlight, not defending it in comparisons to putative alternative technologies.