I just ran into one of the editors from O'Reilly in the halls at Mix and he told me that they just published a "Short Cut" on Silverlight. 

I have not read it yet, but Shawn Wildermuth is very plugged in guy and a proven author so I am sure it is great. 

Getting Started with Silverlight

Getting Started with Silverlight
By Shawn Wildermuth
April 2007 
Pages: 62

Let me know what you think...