The 1.5Gb limitation has been an issue on ThinkPad since late 2008 and affecting Intel chipset as well, it that case, Lenovo had never released an updated BIOS to address that issue until today. If the speculation is correct, it could affect even wider range of laptops shipped (previous gen uMB, uMBP included). MacBook Air and 17" product would not hit this issue is because non of the Apple-shipped SSD option would require beyond 1.5Gb/s, therefore Apple would not incurred issues with high speed data transfer reliability, and Apple does not back third-party SSD support which required SATA 3.0Gb/s.
If there is a hardware bug that is affecting SATA at 3.0Gb/s, it wouldn't be surprised that Apple and Lenovo are quietly downgraded the most popular models first to reduce the percentage of affected units.