People are still talking about web 2.0, I am not sure that is pure technical term. In my understanding, maybe most of meaning of web 2.0 is its marketing meaning. that is, web is becoming commonality and people generate the web's content. Again, i am not sure what is the place of web service in web 2.0, in my understanding, the web is not merely client-server marketing model (I am not talking web structure here), but an interactive community. But question is , who gonna be the operator or administrator of this community or if there are any game rules needed to follow ? will that be another utopian ?

Well, on a technical layer, I'd like to shed some lights on so-called web standard trends

1. front end --
         CSS ----> layout
         XML ----> data 
         XHTML ----> markup
         Javascript & DOM ----> behavior + XMLHttpRequest --> AJAX ?

2. back end -- 
         some open source projects such as Ruby on Rail...

let me know how you are thinking...