Silverlight is coming to mobile, that is Nokia S60 and Windows Mobile. That alone should cover a very big percentage of “smart” handsets. Read up on this short FAQ to get the basics:
http://silverlight.net/learn/mobile.aspx

One of the more interesting Q/As are:
Q: How can I build applications with Silverlight for mobile?
A: There is no difference in how you build Silverlight applications across Web and mobile devices.

The fine folks at BSQUARE have announced that they’ll be porting Adobe Flash to Google’s Android on behalf of a “global Tier 1 carrier.”. Read more here:
http://www.engadget.com/2009/03/25/flash-coming-to-android-courtesy-of-bsquare/