By myself and my colleague and friend Maurice Nafalin. It's finally out, after considerable effort over the last year. It's just published, and I was pleased to see the O'Reilly stand at OOPSLA sold out.
"A brilliant exposition of generics. By far the best book on the topic, it provides a crystal clear tutorial that starts with the basics and ends leaving the reader with a deep understanding of both the use and design of generics." -- Gilad Bracha, Java Generics Lead, Sun Microsystems
Thanks for the kind words, Gilad!