You want to know what requires Java 2, or at least a higher Sun standard than MRJ 2.2 supports? Plenty!!
MRJ 2.2 supports Sun Java standard 1.1.8. All of the tools I have been given at work use either Microsoft-contaminated Java (that's one of the reasons Sun sued MS) or new classes not in the 1.1.8 standard. As a result, I have to run SoftWindows to use the tools and suffer the pitying glances of my co-workers.
I realize that Apple is always going to be a bit behind, because they have to write the Mac kernal from scratch, since Sun only provides a base kernal to Windows, Unix and Linux. Apple's documentation says that only Mac OS X will be able to run their new Java, which is Jave 2 and corresponds to the 1.3.3 standard, I believe. Their was an indication that one of the libraries could be used with Mac OS 9, but nothing was available to try that I could find.
Melinda