It will be usable by anybody who downloads and installs the free, cross-platform, cross-browser plug-in, like 25% of internet users already have, and 25% more will just so they can use my great new thingy.
I'm using the same language and tool-set to create the web site and the services and the Silverlight application, with integrated debugging across the whole thing.
No, no they're not. See, I used to think the very same thing. But then, we were migrated to Lotus Notes three weeks ago. Now I love Microsoft, and want to have its babies :C