Apple has recently released a new developer preview of Java SE 6 for Leopard via the Apple Developer Connection (ADC) site at http://connect.apple.com.
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.