you should read head first at least until first of customize tags for start to do a real little project to examine your know ledge.
i think after you read head first until first of customize tags start writing a small website for example a phonebook with following futures:
if you jump this step successfully then i promise you starting spring 3 .
after learning spring 3 you should learn hibernate.
you often don't need to go depth in hibernate in normal project you should know a normal knowlefge of that.
after that you should learn gwt((before start that learn basics of ajax about a half day)).
then start to integrate spring+hibernate+gwt
there is a alternative for gwt:jsf
you can learn that and start integrate spring+hibernate+jsf