Z-Drive SSDs are shipping in two main flavors: the e84, which uses single-level-cell (SLC) flash memory, and the p84, which employs cheaper and more commonplace multi-level-cell (MLC) flash. Both models can be had with either 256GB or 512GB capacities, and you can get the p84 with a cool 1TB, too.
OCZ makes these products using four-way internal RAID-0 configurations as well as PCIe x8 interfaces aimed at bypassing Serial ATA bottlenecks. As a result, the MLC-based p84 can purportedly hit speeds of 750MB/s during reads and 650MB/s during writes, while the e84 can reach 800MB/s and 750MB/s, respectively.
Don't expect bargain-basement pricing, then. Last time we saw Z-Drives up for pre-order, the 256GB model was priced at over $1,300, and the 1TB p84 was over three grand. Incidentally, OCZ says it offers "unique customization options for OEM clients that may require tailored hardware or firmware solutions for their business." Oh, and there's a three-year warranty.