If you think back how long it took for ATA 33 to make it to ATA 100 you'd be amazed at how quickly LSI is developing SAS 12Gb/s. Less than two years ago LSI released their first SAS 6Gb/s and a year ago they launched their second generation SAS 6Gb/s. Today LSI is showing off early SAS 12Gb/s and it's looking pretty good.
It'll be quite sometime before we see SAS or SATA drives running 12Gb/s but that isn't going to stop LSI from making use of the bandwidth. At AIS 2011 we saw first hand that LSI plans to use the bandwidth to increase performance on external arrays of disks. SAN and DAS will see higher bandwidth in early 2012.
Hardware updates go beyond just the controller cards and expanders. A new SFF cable has been developed to increase bandwidth at the connector level. Above we see the new double stacked configuration and a new quad cable arrangement is currently in development.
What you send up with is a massive increase to bandwidth, now up to 6400MB/s from a RAID controller that should cost less than 1000 USD at launch.