I don’t have Silverlight and it runs just fine here. (Yup, it’s all in my DOM!) Using Silverlight when installed is fine by me — theoretically, it’s going to run faster than having a browser scale tens of images tens of times a second.
I do have Silverlight installed and I couldn't seem to get the site to use Silverlight. Still all DOM as far as I could tell.
It reverts to silverlight if you are using IE (of course, :) )