This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
GWT does support java.lang and java.Util. This gives you the basic Java types including collections and exceptions. Number and date formatting were added with the 1.4 release and I'm sure more support will arrive. One thing to note is that the code must run in a browser so supporting more complex Java packages like database drivers isn't possible.