When updating Java on OSX you may run into issues with Flash Builder afterwards. One of the issues that always forget is to update your Java Preferences ensuring that 32-bit runtimes preferred first for Java applications.
I’ve just started to play around with Merapi and I feel that it adds a whole new dimension to AIR. The Merapi website describes the project best “Merapi is a bridge between applications written in Java and those
running in and created for Adobe AIR™ (Adobe Integrated Runtime™).” Check it out here, the possibilities are endless! 
From Apple “Java for Mac OS X 10.5 Update 2 provides improvements to security, performance and compatibility for Java SE 6, J2SE 5.0 and J2SE 1.4.2 on Mac OS X 10.5.” The full details can be found at Apple.
MXNA