Although OCZ is far from the first to release such a utility, it's the first memory manufacturer to offer such a utility to its users. Inside the SPD EEPROM information such as CAS latency is stored, but other information such as SLI memory certification and the multiple settings for different speeds that SLI memory offers.
A Russian website has had a utility called Thaiphoon available for quite some time and it enables similar options on none OCZ modules. The difference with SPD-Z is that your warranty is still intact, something it wouldn't be if you used a third party utility such as Thaiphoon.
"Tweaks of hardware and firmware have become the primary tool of most computer hardware OEMs to differentiate themselves from the field of competitors, however, in some cases at the expense of compatibility," commented Dr. Michael Schuette, VP of Technology Development at OCZ Technology. "OCZ's answer to the fragmentation of the market is the patent-pending SPD-Z technology that allows users to select custom SPDs from a library to optimize the interaction between the motherboard and memory firmware."
You can download SPD-Z here