The install base of silverlight is pretty low, but way higher than I expected. Its hard to get hard reliable numbers but I've seen from 50% all the way up to 70% or so. Its much higher than I expected, but not high enough to count on. I don't get the draw when flash has an install base in the higher end of 90%. Once again its hard to get reliable numbers, but there is no doubt it trounces silverlight.

Even java plug-in install base beats silverlight's which is pretty bad. I know netflix and mlb.com use it, but I don't know a lot of others. I'm sure they are there, but it doesn't scream lively tech to me.