Apple has released a firmware update for the MacBook Pro models that were released in June of 2009. The patch notes say that, "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."
In other words, Apple is addressing an issue with using those drives, but is leaving them officially as unsupported devices.
The firmware update is a 3.35MB download, and if you have a June 2009 MacBook Pro unit, you will find it in Software Update. You can also download it from the Knowledge Base article for the update.