Aggregate sizes in Data ONTAP 8.0 (7-mode) can scale up to 100TB in capacity (depending upon model of storage system). This is much higher than the 16TB limit found in 32-bit aggregates of earlier versions of Data ONTAP.
See new technical report here:
A Thorough Introduction to 64-Bit Aggregates
So I occasionally get the question, "why 16 terabytes?" In ONTAP 7, address pointers are 32 bits in size, given the standard 4 kilobyte block size -- thus (2^32 - 1) * 4KB = 16TB.
Now with 64-bit addressing in ONTAP 8, it's possible to realize better performance (due to higher spindle count) and easier management (fewer number of aggregates per storage system).