For now a simple workaround is to plug any hard drives or optical drives into the unaffected SATA III 6Gbps ports on your motherboard. But Gigabyte is aware not everyone knows how to do that and has come up with a simple utility to guide less tech-savvy users. Interestingly, it seems the utility isn't tied solely to Gigabyte motherboards either.
Essentially the Gigabyte 6 Series SATA Check tool will detect any devices hooked up to the SATA II 3Gbps ports and provide guidance as to which ports to use instead. Needless to say the utility does not fix the problem with the chipset, but merely makes it super-easy to identify whether you're using the affected ports or not. In case you are using three or more SATA devices the company reasonably advises users to prioritize important devices on the SATA III ports (e.g. the hard drive with your operating system on it), and the less important devices on the SATA II ports (e.g. a DVD ROM).
Revised P67 and H67 boards are expected to begin appearing in April and manufacturers should start offering replacements accordingly. In the meantime, if you are already stuck with one of the faulty ones and need some help with your SATA ports -- or know someone who does -- you can get Gigabyte's 6 Series SATA Check tool here.