The "hello world" example is incredibly uninformative. What does that have to do with "structured web programming"? Where is this printed out on a web page? Does the console output there correspond to the html output? Or some other console?
The "Hello, Dart!" is written to a console emerging from underneath the code sample.
https://code.google.com/p/dart/source/browse/branches/bleedi... is a more DOM-oriented version of the same program.
http://www.dartlang.org/docs/technical-overview/index.html#h...