Tomas Zezula from NetBeans team has created a project template for Google Web Toolkit. I've been playing with it and it gives you basic support you need for GWT. You can create a new GWT project (as a web application) and the wizard prepares the directory structure for you. By running the application Google's SDK is launched and you can run your application. See screenshots:
GWT in NetBeans
The module is available in CVS in contrib/gwttemplate. The support is quite basic, but it's a good start. For those who have a hard time checking out CVS and building the module (it's easy, but takes some time), here's the nbm for download
. Just install the nbm and create a new project - Web | Google Web Toolkit Application. The nbm works both in 5.0 and 5.5.
Also, don't forget about the cool support for jMaki in NetBeans