Same as everybody else really. Everything from beach ball and unresponsive apps to failing to find the disk at boot. Tried the disk in other laptops, seemed ok, tried other disks in the MacBook, none worked. Install/recovery tools from MacOSX DVD didn't see the disk.
I was afraid it was the main board, but I spotted a few dents on the cable, searched the cable part number and ended up here. All the other repair stories were helpful in confirming that it was very likely just a cable problem.
Pretty easy fix. MacBook is back to working fine. Very happy, but considering backup solutions now :)
I decided not to use the adhesive strip on the cable to the IR receiver. It seemed like it would be hard to get right, and if I had to pull it out to adjust it I was afraid I'd damage the new cable. And the disk and brackets on the cable seem like they should be able to hold the cable down just fine.