For the work that I've been doing on a Google product that is built with GWT, I put together a breadcrumb navigation widget. The design is based on a delegate approach (similar to Apple's pattern for UI widgets in Cocoa and Cocoa Touch) where the user of the widget provides a delegate that returns a Collection of navigation items (for now it's just a wrapper around the text, target, and tooltip to be displayed using Hyperlink), a page title (displayed using Label), and a page detail (also displayed as a Label). The delimiters between nav links can be overridden as can the delimiter between the page title and description fields. An example of the layout would be:
Sports > Professional > Baseball > American League > Yankees or Sports > Professional > Baseball > American League > Yankees > Player: Babe Ruth --~--~---------~--~----~------------~-------~--~----~ http://groups.google.com/group/Google-Web-Toolkit-Contributors -~----------~----~----~----~------~----~------~--~---
