Totally agree... And yes, a kickass app would be great, but let's not forget the commercial side of the GWT framework like mentioned above, that is: making a product/framework that is awesome, is nice, but making sure people use it, is another thing... This is the risk of many technical driven products/framework... Many products/frameworks died slowly because of this...
Especially now that Google put GWT on it's "feet", how is this commercial aspect filled in?
I think you have to target two type of persons:
1) The dev people: Kickass app would be a good start... but still, dev people don't want to read these days and see something on their display within seconds, so there must be "something" to do this. Maybe let the kickass app contains severy modules that one can start with that has an associated HOWTO/blog/doc....
2) The decision makers. These are often the people that "hear" something about a product/framework and push it to the dev people on the floor (even if they don't like it, they must play/use it)... Let's not forget to get in "touch" with these people as they are very important IMHO.