ONTAP 8.1: What you care about.

DATA ONTAP 8.1: What's new that you care about.

• Hugely improved parallel processing software.  You should see big improvements in what your CPU's are capable of. 
• In-place, online 32-64 bit aggregate conversion. Woot!
• 160TB aggregate limits on 3200 and 6200 series.
• Support for SnapMirror across clusters.
• Support for SAS shelves in 7-mode metrocluster.
• Cluster mode support for NFSv4.
• Cluster-mode support for dedupe, 7-mode and Cluster-mode support for compression.
• Cluster-mode support for SAN (FC and iSCSI).
• Cluster-mode support for non-disruptive OS upgrades.
• Cluster-mode support for FlashCache.
• Cluster-mode support for SnapMirror?
• Cluster-mode support for up to 24 nodes (only 4 if SAN).

Interesting: compression runs before dedupe.