ECMA - the new four letter word

When something essential is purposely flawed.  Derived from the standards body that regulates javascript/Jscript and Actionscript3, the most widely used client side programming languages on the Internet today. 

I've been asked, "What programming language should I master"?  Naive question for sure but it got me thinking about the browser as the new desktop and more specifically about client side RIAs.  A new religious war is bubbling . . . Flash or Silverlight.  Some frame it as an open source v. Microsoft battle.  However, that does not take into account the client side operating system (including Symbian here) and the server side technology.

This opens a very interesting door for the likes of Laszlo.  If they pretty themselves for a date with Google, I think they can come out on top.

Back to server side technologies.  Besides Livescript which ran on Netscape web servers, I don't know of any server based language that is ECMA compliant.  FMS doesn't count because it doesn't serve http.  What language am I missing?  Haxe really doesn't count . . . at least not yet. 

So if all the client side technology is ECMA based, is there an equivalent server side language?  If so, then ECMA would be good programming "language" to master because learning the different dialects would cover you as a newly minted CS graduate.  It would also get you a running start with Python and Java.

Having one standard to rule them all is great but if ECMA is that standard, it is inherently flawed.  A beautiful dilemma.