In a note with the latest Mac OS X 10.5 software update, I read this blurb about Apple's Mac Java support:
Java for Mac OS X 10.5 Update 6 delivers improved compatibility, security, and reliability by updating J2SE 5.0 to 1.5.0_22, and updating Java SE 6 to 1.6.0_17 for 64-bit capable Intel-based Macs.
J2SE 1.4.2 is no longer being updated to fix bugs or security issues and is therefore disabled by default in this update.
Put another way, Java 1.4.x on Mac OS X is dead, long live Java 1.4. Not huge news, but noteworthy.