Microsoft Silverlight is a new powerful web content language designed to compete directly with Adobe Flash. It has all the same features as Flash, aside from the ability to use 3-D acceleration on the client computer, but does have an advantage in its ability to interact directly with web page content outside of itself. It has the ability to be crawled by search engines, something that isn't possible with Flash, due to the fact that it stores all text in an XAML database rather than it being built into the application. It is currently compatible with Internet Explorer 6, 7, and 8, Mozilla Firefox, and Safari for Windows 2000, XP, Vista, and Server, as well as Apple OS X.¬†Currently, official compatibility is planned for Opera. You can get it to work in Opera right now with a hack on the Silverlight client, but it is not supported my Microsoft, and could break your browser.
There is also a project called Moonlight that is being developed for the sole purpose of running Silverlight applications in browsers on the Linux platform. Surprisingly enough, this project is endorsed my Microsoft, and it's developers have access to the specifications, which will mean the Linux client has a better chance of being stable versus most Linux applications that have been reverse engineered from closed source software.
It seems like Silverlight is going to be around for a while, and it might even take a good share of web content away from Flash, due to its SEO capabilities. If you have a Silverlight application you would like to deploy, and are looking for a host that can do it, go ahead and give our Sales line a ring. We will be happy to answer any questions you may have.
Learn more about Silverlight at http://www.silverlight.net.