Last night I made a simple Silverlight maze generator for my 6 year old daughter, who's really into mazes right now. When I tried to print the resulting mazes, I found that the Silverlight content was was blank in Firefox (left), but worked in IE (right):
The official word seems to be that printing Silverlight 1.1 content is unsupported, but is being considered as a 1.1 feature. It sounds like some people are coming up with some clever hacks to handle printing Silverlight content, but I'm hoping that print support is added to 1.1. In addition to a nice application framework, Silverlight's vector based content could be a great print format which would eliminate the need for PDF downloads in many cases.