There has been speculation (and here) that Sun's ZFS filesystem is included in Apple's server operating system plans.

An Apple spokesperson writes in response to a query about possible ZFS support in Apple's forthcoming Leopard version of Mac OS: "Feedback from Eric Zelenka who presented at the (Leopard) briefing (in December) is that Apple has not announced plans to include ZFS in Leopard or Leopard Server."

It doesn't mean that Apple won't announce plans. Wait for the January 9 MacWorld Expo in San Francisco where more information might be available.