...and Microsoft already had WPF... Isn't everything else VERY primitive compared to it? Why would they go back to an inferior technology? Adoption issue?

Microsoft had JScript.NET even before C#, so this was purely a political move not a technical one.

At that time , investing on javascript would not have made Windows sell more.

Now Javascript is seen as a way for MS to get more apps on their RT plateform thus sell more Windows licenses.

However , i dont believe MS javascript move is a long term one.

Wasn't Mozilla the one pushing for ES4?

hi, actually it was Adobe, they worked with mozilla on tamarin a es4 vm.

Take a look at CoffeeScript if you want python-like style..

or livescript if you want haskell-like style [http://gkz.github.com/LiveScript/]

it's a coffeescript descendant rather than a haskell->js compiler, but it has a very pleasing haskell/ml surface.