Silverlight is awesome to deploy. As this forum thread describes, you basically just need your web server to setup the right mime type ("Extension should be .xaml and the Content Type should be application/xaml+xml". I also had ".dll --> application/x-msdownload" because some other blogs recommended it).
You can then just ftp the files from your silverlight project (ClientBin, files in the root folder, and any other directories), to your server.
After dealing with Winform, ASP.Net, and XNA deployment problems, I was floored that it just actually worked.
Because Silverlight runs on the client machine, it is the client's responsibility to have the right stuff installed. However, silverlight makes that really easy by rendering as a single-click download link if the client doesn't have it installed yet.
Also note that Silverlight is not a server technology like SQL2005 or ASP.Net. You don't even need an ASP.Net server to run Silverlight. (This is especially practical if you're a hobbyist on a budget, and your host company charges extra to asp-enable your site.).