Why are Google and Microsoft developing Javascript compilers?
As web applications grow more and more sophisticated, with lots of user interaction, it gets harder and harder to hand code it all in Javascript. Back when Javascript was conceived as a macro language for web pages, web apps were much less interactive than they are today. So even though it is possible to write very complex applications directly in Javascript - it is hard work and to most programmers is just not practical.
Applications such as Google's Gmail or Microsoft's Live products depend heavily on Ajax (Asynchronous Javascript And XML) - a now common Web coding technique that allows the creation of complex, interactive web pages that do not have to be completely reloaded from the web server to update. This technique, though not overly complex to implement, requires a lot of coding.
So in order to create complex web applications, as well as maintain and evolve them over time, solutions such as 'high-level language to Javascript' compilers have come into play. These products allow developers who are not familiar with Javascript - and indeed may even have no idea what Ajax is - to quickly develop complex applications by writing in the language they are already familiar with. It's the old 'write once, run anywhere' scenario. In Google's case this is Java, in Microsoft it appears C# will be the choice, and in Morfik they handle C#, Java, Pascal and Basic (for VB).
We can also see the larger J2EE vs .Net battle involved in this - Google choosing Java and Microsoft of course going with C#. So both will only support one language seriously, because they're busy fighting with each other. This possibly opens up an opportunity for Morfik, which supports more languages. Time will tell I guess.
One final thing, looking at it from a higher level - GWT allows Google to hire more Java developers to do web app coding, rather than Javascript developers. I'm no expert in the programming job market, but I'm guessing skilled Java developers are more plentiful than skilled JS developers. So GWT is a smart move for Google, because it allows them to have a much bigger pool of programming talent to choose from.
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