Oracle and Java issued a joint announcement today that Apple has donated the code in their implementation of Java to Oracle and that Oracle will pick it up as a major new platform in OpenJDK. Apple also announced that OS/X Lion will ship with the existing Java 6 platform that Apple has controlled.
It's not all wine and roses. Oracle has stated that pulling in a whole new platform is non-trivial and that when OpenJDK 7 ships, it will not initially have support for OS/X. They say it's too early to say how much additional time will be required to support OS/X in OpenJDK. I assume that acknowledging that fact is the reason Apple has committed to shipping Java 6 with OS/X Lion.
The overall takeaway from this is that OS/X will have a supported Java implementation and will not be left in the lurch. It also means that OS/X will continue to lag behind the Java versions on other major platforms for the next year or two. Presumably once OpenJDK ships with native OS/X support, OS/X will become a first-class Java citizen.