One of the big ones I can think of is that the web is becoming a system of platforms, Twitter, Facebook, Google etc. are all platforms, when I build web application it is almost guaranteed that my app will be a JavaScript based UI that couples those platforms services into a work flow with my own platform in some novel way. The way we build apps is changing they are becoming UI's that front end the cloud where the cloud is an assortment of services that provide data and content from different sources. JavaScript is a key enabler in the new web as a platform.