O’Reilly have an in depth article on their site by David Flannagan, author of the Java in a Nutshell books now in 5th edition to cover Java 1.5 language changes, on the use of Generics.
I’ve always found the Nutshell books to be an excellent desktop reference, plus the introductory chapters give a very concise overview of the language features in Java. Click here for more details on Java in A Nutshell: