Yeah, it sucks when hardware fails, but it can happen to any hardware by any vendor. Hopefully it is just something simple like the hard drive causing problems across the bus, and not the actual controller. Remember to keep an eye on the system logs, as they can be a great indicator to problems like a hard drive issue. You can do this via dmesg to see the kernel log in memory, or look at /var/log/system.log for the one written on the disk.

Are you sure you weren't carrying the Mac around in your pocket with something sharp near it? *ducks*