The 256 GB version is available now, while the 512 GB version will be available in the 3rd quarter of 2007. No specifics on price yet, but they estimate it will drop to around$2 per GB by 2012.
Flash drive means that this is solid state, no moving parts, like the ipod nano (which has a current maximum storage of 8GB). Less to break, and not nearly as much resource consumption on power and cooling costs.
And, about 200 times faster than the average hard drive. "While hard drive access times are measured in milliseconds, access times for Zeus-IOPS are in microseconds, enabling a significant increase in server processor utilization. Additionally, Zeus-IOPS SSDs are more than 200 times faster at random transactional performance than a 15K RPM enterprise hard disk drive, providing lower cost per transaction and enabling higher performing systems with far less hardware costs."