Sure, it should be working once you download & install Silverlight.
I am unsure what could be the case, lets be sure that silverlight is generally working.
Can you check whether other examples from
http://www.silverlight.net/showcase are working for you, and its only ICMIZER that isn't?
I think there may be a general problem with Silverlight being incorrectly installed, or maybe disabled.
Also try using Safari browser or downloaded version of ICMIZER, once it runs, as Mac Chrome has a bug with Silverlight which isn't fixed yet and any Silverlight application on Mac & Chrome can have problems while running.