I just participated in a seminar on the new features in the Java 1.4.2 language, and new planned features for the Java 1.5 language. Here is a list of URLs that I used in the research for that seminar:
Java 1.4.2 and 1.5 Roadmap
http://developer.java.sun.com/developer/technicalArticles/RoadMaps/J2SE_1.5/j2se_1_5.html
The "JDK 1.4 Tutorial" book referred to in the seminar
http://www.manning.com/travis/
The Pattern class (including gegular expression constructs)
http://java.sun.com/j2se/1.4.2/docs/api/java/util/regex/Pattern.html
Introduction to regular expressions (article)
http://developer.java.sun.com/developer/technicalArticles/releases/1.4regex/
Performance documentation for HotSpot
http://java.sun.com/docs/hotspot/
A JavaWorld article discussing new garbage collectors
http://www.javaworld.com/javaworld/jw-03-2003/jw-0307-j2segc.html
Brief discussion on new GCs
http://www.javaperformancetuning.com/news/qotm026.shtml
The JVM tools that were demonstrated, including jvmstat and visualgc
http://www.sun.com/coolstuff
The Java Community Process home
http://www.jcp.org/