All high speed serial protocols we're speaking of, including SATA/eSATA, IEEE1394, USB, and Fibre Channel all use
8b/10b encoding, which transports 8 bits of user data by transmitting 10 bits of signalling data on the wire. Thus, 10 clock cycles of the wire transport must be used to transport only 8 bits of user data. This is why all the figures are divided by 10, not 8.
This means that the numbers in parenthesis represent the raw signalling rate of the transport medium, while the numbers outside parentheses represent the theoretical amount of user data that can be transported.
SCSI is a parallel bus, not high-speed serial, and does not use 8b/10b encoding.
(I did go back and edit the Fibre Channel number, the raw signalling rate for Fibre Channel 4GFC is 4.25 Gb/sec, not 4 Gb/sec).
Also see
Wikipedia's Storage Bandwidths for additional details.