Apple states the update delivers improved reliability, security and compatibility.
The update addresses multiple security vulnerabilities in each of the three versions of Java that can allow privilege escalation so an untrusted applet may run with the privileges of the current user.
It also addresses a vulnerability that allowed a malicious Java Web Start application to cause arbitrary code execution.
The update still leaves the Mac's version of Java behind other platforms. For example, the current version of Java SE 6 is 1.6.0_16.
The good news is that _16 does not include security fixes, though it does contain the latest time zone data, and that could be important to some applications in particular geographical locations.
While Sun releases Java for the other common platforms, the Mac version is put together by Apple. Consequently, Java for Mac tends to lag behind the other implementations.
• SuperDrive Firmware Update 3.0 (eliminates optical disc noise on startup and wake on recent iMac and Mac mini models)
• Mac OS X Server 10.5.8 Update v.1.1 (multiple fixes)
• Mac mini EFI Firmware Update 1.2 (improves compatibility with the latest Apple memory kits)
• Server Admin Tools 10.6 (tools to administer Mac OS X Server 10.5 and 10.6 from a Mac running Snow Leopard)
These updates are available via Software Update or Apple's Support Downloads page.