Word to the wise: DON’T use the new kernel packages I prepared. They will cause spurious lockups when disk activity rises over a certain level. The libata/ATAPI code is not ready for prime time. John Linville said as much in the bug I referenced, but I wanted to try it anyway. You should back down to the standard kernel, 2.6.12-1.1456_FC4, and use that.
I am preparing new kernels that are essentially repackaged versions of the standard Fedora kernel, so anyone who updated to mine using yum will be reverted to the old (buggy, but stable) behavior.
UPDATE: Apparently I needn’t worry, since the official channel just released 2.6.12-1.1526_FC4. The odd ICH6M-related SATA behavior, unfortunately, persists.