I don´t like Java for games, especially web games a lot either.
Regarding silverlight its not interesting to me right now because it is too similar to flash on weaknesses side (and then adds various more own ones), has too few additional and important strengths and overall seems too much in infancy state to be worth considering for me.
MS sure has the force to be able to change all that in a rather short timespan,so yes, it could be more interesting in a year or two.
If it can ever reach capabilities like XNA or Unity? I don´t think so.
If it can become more interesting than flash when its about doing similar things as in flash? Hm,maybe, to me still not really likely.