Rossi writes "Jonathan Schwartz today confirmed that Apple has ported ZFS from the Open Solaris project and that the file system will be available in OS X 10.5. He also mentioned that Apple would make this announcement at the WWDC next week. Does this spoiler arrive suspiciously after Steve Jobs announced Java wouldn't be available on the iPhone?" Link to Original Source
If it happens once, it's a bug. If it happens twice, it's a feature.
If it happens more than twice, it's a design philosophy.