Ken, gwt-log is only intended for logging on the client-side, same for GWT.log(). Basically if something bad (or good) happens in the browser, it will send a message back to your server. Your application server should be configured for logging with log4j or other logging package. So, on your server you might have server.log - this is where you might get the remote log messages.
In your servlet classes, you would simply instantiate an instance of a logger, such as log4j. Something like:
Logger log = Logger.getLogger(MyClass.class);