Apple has released version 2.2.1 of Xcode, "Apple's tool suite and integrated development environment (IDE) for creating Mac OS X Universal Binaries that run natively on PowerPC and Intel-based Macintosh computers. The IDE provides a powerful user interface to many industry-standard and open-source tools, including GCC, javac, jikes, and GDB. Xcode is designed to fully support the Carbon and Cocoa frameworks and Java. It contains templates for creating applications, frameworks, libraries, plug-ins, Java applications and applets, and command-line tools. Developers can use Xcode to construct a user interface, test code performance, and perform many other common development tasks." 2.2.1 is a bug fix release. Mac OS X 10.4 (Tiger) is required. Xcode and its updates are free beer. With Mac OS X Apple wisely stopped charging for developer tools. You'll still need an ADC membership (including the free membership) to get a copy.
Apple has posted the fourth beta of Java 5 Release 4 for Mac OS X 10.4 (Tiger) on the Apple Developer Connection (first born child required). This is based on Sun's J2SE 1.5.0_06. It also uses Sun's rendering by default instead of native Quartz graphics. (This will probably change again before final release.) Most importantly it finally makes Java 1.5 the default instead of 1.4. "This release is not compatible with the Intel-based Developer Transition Systems" One hopes it's compatible with the MacBook and the Intel iMac, but I don't really know.