The GWT4NB project aims to enable developers to take advantage of both: the superior support for creating Web Applications built into the NetBeans IDE and the power of GWT (Google Web Toolkit).
Click here for the full list of the features with screenshots.
WARNING! Although built on top of the web application support as a web framework, GWT4NB does not support all the features implemented in NetBeans for normal web applications. For example, you cannot currently define multiple source folders or rename the build.xml
See also Ohloh
JDK 1.5 and 1.6, GWT 1.5, 1.6, 1.7, 2.0 and 2.1M1, NetBeans 6.7.1, 6.8 or 6.9 (older/unsupported releases)
there is only one branch (stable) from which nbm files are produced regularly (weekly) and uploaded to the "Documents & Files" section. If no serious bugs are found in a release during a month, it will be uploaded to the beta auto update center and will be available through the default NetBeans update mechanism. See the list of update center requests for more details.
Download NetBeans 6.8, checkout the sources from Subversion and open the project in NB.
Tip: on Windows 64-bit you have to either add run.args.extra=-J-server to your nbproject/private/private.properties or use 32-bit version of the JDK as there is no client JVM in 64-bit JDK 1.5

The NetBeans IDE is a free, open-source Integrated Development Environment for software developers. The IDE runs on many platforms including Windows, Linux, Solaris, and the MacOS. It is easy to install and use straight out of the box. The NetBeans IDE provides developers with all the tools they need to create professional cross-platform desktop, enterprise, web and mobile applications.
Google
Web Toolkit (GWT) is an open source Java software development
framework that makes writing AJAX applications (...) easy for
developers who don't speak browser quirks as a second language. Writing
dynamic web applications today is a tedious and error-prone process;
you spend 90% of your time working around subtle incompatibilities
between web browsers and platforms, and JavaScript's lack of modularity
makes sharing, testing, and reusing AJAX components difficult and
fragile.
GWT lets you avoid many of these headaches while offering your users the same dynamic, standards-compliant experience. You write your front end in the Java programming language, and the GWT compiler converts your Java classes to browser-compliant JavaScript and HTML.