"About MacBook Pro EFI Firmware Update 1.7
MacBook Pro EFI Firmware Update 1.7 addresses an issue reported by a small number of customers using drives based on the SATA 3Gbps specification with the June 2009 MacBook Pro. While this update allows drives to use transfer rates greater than 1.5Gbps, Apple has not qualified or offered these drives for Mac notebooks and their use is unsupported. "

Hopefully users applying this update don't have the problems many did with the last MBP SMC firmware update. (The one for pre-unibody MBP's that were in the flawed nvidia 8600M production range.)
FYI/Warning: An Apple forum thread (June 2009) had quite a few people reporting problems after this update, typically with upgraded/replaced (non-OEM) drives (including some WD, Seagate and some SSD drives).