Combine this news with the announcement of the App Store for OS X, and one possible conclusion is that Apple doesn't want Java-based apps in the app store. It's an easier prohibition to make if the JVM is not officially supported by Apple.
Also, this could be a guard move against Oracle, a capricious litigator.
2.24 "Apps that use deprecated or optionally installed technologies (e.g., Java, Rosetta) will be rejected"
It doesn't explicitly e.g. it, but Flash isn't installed by default either on the new MacBook Airs, so I'm guessing you can't do a wrapper around a SWF either.
That's a very clever move. If you don't want your app store to distribute Flash based programs, just make it so that Flash isn't installed by default. Since it can be installed by users, most people won't notice. But they can legitimately claim that Flash is an optional component...
One thing this enables is switching platforms. If a future MacBook Air runs on ARM instead of Intel, anyone using Xcode would only need to recompile to target the new platform. Similar to how Intel support was easy for Xcode developers (but very hard for Metrowerks developers). Getting everyone on Xcode gives Apple tremendous flexibility. They could even have apps target LLVM-IL (whatever it’s called) instead of the CPU directly.
Also, this could be a guard move against Oracle, a capricious litigator.