Thanks for pointing out these specifics. The Java class libraries that comprise the GWT API are included under an Apache style license, but the Java-to-JavaScript compiler and hosted web browser have different licensing restrictions, as summarized at: http://code.google.com/webtoolkit/download.html .
This site points out that "the code you create with GWT is yours. Google does not assert any intellectual property rights to code or content that you create using GWT." To answer any remaining questions a developer might have about the GWT's licensing ramifications, however, you would have to delve into the fine print and/or have a lawyer look at the entire license's language.