Though Microsoft Silverlight is a cool technology, it pales in front of Adobe Flash (98% of browsers have it) in terms of availability. It is not an unique MS problem, it is a problem for any new offering when there is an incumbent who has a majority market share. To change this requires education, awareness creation and put it in front of users at many as possible in exchange for an added value to them. I was pleased to see Microsoft doing some steps in this direction (unlike their pathetically nil action to have .NET Framework Runtime in desktops widespread in its earlier days) by having a beta of Silverlight enhanced downloads when people come to MS Download Center site. 

Read the complete post at http://www.venkatarangan.com/blog/2007/12/24/Silverlight+Penetration.aspx