To their credit, Apple addressed complaints about a downgraded, slower SATA interface on their new MacBook Pros fairly quickly. Unfortunately, that hasty firmware update seems to be causing much more serious problems. For example! Not recognizing common hard drives.
A rapidly growing thread over at Apple's Support site is brimming with people reporting that the new firmware update—which simply jacks up the MacBook's SATA interface to a maximum potential bandwidth of 3GB/s, like in older models—causes their laptops to fail to recognize a wide variety of third party hard drives, leaving their computers effectively crippled.
You could argue that Apple's firmwares don't necessarily need to accommodate whatever modifications and third party hardware users might subject them to, but in this particular situation, that logic doesn't hold. The only way to even notice the MacBooks' decreased 1.5GB/s bandwidth would be to install an ultra-fast, aftermarket SSD, so Apple's firmware update was a response to its users' desire to use third party hardware. From the looks of it, this particular hiccup will affect more users than the first one, so Apple should be—pending an investigation—obligated to fix it. Should.
If you haven't applied the first update, Adam's initial advice has turned out to be very prescient:
If you're not planning on swapping in an SSD, you don't need to worry about this firmware update.