I think the 64GB X25-E has already been released and is for sale (check Amazon).
I'm thinking about buying another 32GB, though, and striping them for the IOPS. I'm trying to convince my wife that it'll just be cheaper to get it over now ("the greedy man pays twice...")
As regards the 8 adversus 10 thing - bitesize is right: 1 gigabit is 8/10 of a gigabyte (thus 8 in a 10 wrapper) and, in any event, SATA 3.0 refers to 3 gigabits not gigabytes.
As regards the 250 MB/s "spec" for the X25-E, I can only rely on my actual experience -- and I just tested it again and bitesize was, again, right; this time its 272.
A bus with a theoretical max of 3Gb/s is highly unlikely to ever actually transfer 3 Gb/s. My conclusion is based, in part, on the fact that running the same tests on my MBP 17" 4,1 (SATA 1.5/I) gave me the same kind of consistent results at 137 MB/s -- both MBP(s) were tested under real world conditions (read: tests running in the background while I was doing real work). Coincidental... perhaps. But I would like to see a single drive put 1.5 Gb/s through the SATA 1.5/I bus or 3 Gb/s a second through the SATA 3.0 bus. Let me know if you have any examples.
Whatever the case, the sequential reads and writes are not critically important to me -- IOPs are what I 'm after and the X25-E beats my four disk, RAID 0, array of 320GB Scorpio Blacks by an embarrassing margin. Reads per second: 4 disk array 7-800 -- X25-E 7500-9000; writes per second: 4 disk array 65-100 -- X25-E 3 -3200 writes per second (again, all under real world conditions). Check that random disk test score on XBench -- I think it was in excess of 800. That seems pretty good to me. But back to the actual topic (i.e. not whether the X25-E is saturating the bus, about which I might have been wrong, but whether it is the fastest SSD), if you know of a faster SSD (that is in 2.5" form factor, e.g. not the almighty Fusion IO), please, please let me know. If you haven't gathered, I'm a speed freak.