SATA2 is supposed to refer to 3Gb/s / 300MB/s transfer rate. so at the bottom it says Serial ATA-300.
I believe SATA II (the old name for the SATA standards organization, now SATA-IO) was misinterpreted as a name for a new standard for faster transfer rates. This is more properly called SATA 3Gb/s or SATA-300. I would assume SATA2 is meant to differentiate itself from SATA II, but I don't beleive it's correct.
Consider that the next standard is going to be 6Gb/s ... are they going to call it SATA3 by mistake as well? Because if you ask me, SATA3 might be misinterpreted as 3Gb/s
Bit of a messy matter, if you ask me.