I am using Eclipse 3.4.2 with the latest GWT. The IDE doesn\'t even switch to Debug Perspective automatically.
I was also following the StockWatcher guide on the GWT website and then got to the Debugging part of the tutorial and I could not get my breakpoints to trigger until I stumbled upon the SDBG plugin. I installed the plugin and followed the video and it worked!
Make sure to make a Debug Configuration and use com.google.gwt.dev.DevMode as your Main class.