Not a lot. To assuage my fears, I just built OpenJDK's BSD port and ran Eclipse 3.6.1 on it without X11 (This from Snow Leopard 10.6.4). It wasn't hard, and could easily be packaged for general consumption.
The maintainer of the OpenJDK binary packages for OS X, SoyLatte, recently tweeted that "A community supported Java implementation for Mac OS X (including native AWT/Swing) is a totally tractable problem." (http://twitter.com/landonfuller). Even if Oracle doesn't step up, it seems the OS X Java community will probably handle it. Moreover, since Java has been languishing at Cupertino for years now (the length of time till Java 5 shipped, Java 6 32 bit), it's likely the community will handle it in a better way, with more frequent updates, than Apple ever did.
Until it's something that's a DMG file that anyone can grab and is indicated to work on 10.6, it won't be a real solution for most people.
The soy latte stuff makes you type in a 'iam not a crook' license code to download, and only mentioned 10.4 and 10.5. It gives every indication of being a garage-hack-only thing for bleeding edge BSD grey beards, not something that is a drop-in replacement for current OSX users.
I want to use it - I tried soylatte last year - didn't work well enough for my purposes on 10.5.
I agree - it's not, at the moment, an ideal end user situation. Even though the build process was reasonably easy, a fair few GUI programs won't run (though mostly every command line app seems to work fine). Most importantly for my test, Eclipse was OK.
The main point of the test was to see how close the system was to being even usable. Considering Apple have maintained the OS X Java for a decade, I expected there to be no alternative that was even vaguely close to running "Hello World", let alone running something as complex as Eclipse. Instead, it worked pretty damn well, and (modulo licensing), I suspect even I could package up the results into a DMG that 95% of people could use to, i.e., build Android apps. More than that, consider the worst case scenario for OS X Java...
1) Apple don't ship anything with 10.7; 2) Oracle don't ship anything, nor do IBM; 3) Getting old versions of Apple Java running is impossible
Then, the real community experts have a nearly whole year of lead time (until Summer 2011, the earliest Lion ships) to convert what already limps along quite well into a decent Java SE SDK and runtime experience. This seems well within the grasp of them. Of course, if the community doesn't step up because it's not interested, then that rather makes the point that Java on OS X just isn't relevant any more.
So a default linux install shouldn't support perl? If OS's supported Java from the install just like they support exe's people wouldn't have to deal with downloading and configuring a runtime.. it would eliminate update managers and configuration issues.
The maintainer of the OpenJDK binary packages for OS X, SoyLatte, recently tweeted that "A community supported Java implementation for Mac OS X (including native AWT/Swing) is a totally tractable problem." (http://twitter.com/landonfuller). Even if Oracle doesn't step up, it seems the OS X Java community will probably handle it. Moreover, since Java has been languishing at Cupertino for years now (the length of time till Java 5 shipped, Java 6 32 bit), it's likely the community will handle it in a better way, with more frequent updates, than Apple ever did.