I found it interesting that the exception was not for Javascript, but rather for WebKit in general. "The only exception to the foregoing [ban on downloading and interpreting code] is scripts and code downloaded and run by Apple’s built-in WebKit framework." [from section 3.3.2]. Perhaps Apple wants to keep their options open for other scripting languages in WebKit. I would love to see python and ruby scripting on the client side, personally.
What about, say, Haskell compiled to JavaScript?
If it runs on their JavaScript engine outputting to their HTML component, it's fine.
Why not a Python interpreter written in Ruby running under Silverlight?
Would you mind linking me to where it says that? I can't find it.