Java is an important technology included as a core feature of Mac OS X, and Apple puts forth extensive effort to make sure Java performs well, is reliable, compatible, and secure. Every Mac running Tiger or Leopard has great support for the most widely-used versions of Java, both Java 1.4.2 and Java SE 5. These versions are regularly updated with security fixes and compatibility improvements to support the widest collection of Java applications in production.
The Java SE 6 release for Leopard is targeted at Java developers. This version of Java for Mac OS X requires an Intel-based Mac capable of running 64-bit applications, including computers with Core 2 Duo processors and any Mac Pro computer. Java SE 6 takes advantage of Leopard's 64-bit capabilities to offer unique performance capabilities for current and future generations of Macs. Please see the release notes included with the Java SE 6 download for additional information about this preview release.