Luis-Miguel Alventosa announced exciting news: VisualVM 1.0 is now being included in Sun's Java SE 6 implementation as of Update 7. His announcement is available in his blog. VisualVM is a highly useful tool because it consolidates many command-line performance and diagnostic tools that were previously available as separate, non-visual tools in previous versions of Sun's JDK.
I was happy to see Sun include native JAXB support and native annotations processing support in Java SE 6 and even wrote an article for OTN about that. Like VisualVM, JAXB was available for separate download before its inclusion in Java SE 6, but having it integrated in the JDK provided several benefits. Similarly, having a platform JMX agent (introduced in J2SE 5) was also significantly more convenient than using a separate JMX implementation. I expect to realize similar benefits from having VisualVM downloaded as part of the JDK. There is no concern about downloading or configuring VisualVM separately and it can be run simply as %JAVA_HOME%/bin/jvisualvm or $JDK_HOME/bin/jvisualvm (assuming that JAVA_HOME is defined as an environment variable pointing to your JDK 6 Update 7 installation). Because many of us have that directory in our path anyway for convenient use of java, javac, xjc, jconsole, and many other commonly used Java tools, this is especially convenient.