After a long wait, Coriolis Systems has released new versions of iDefrag and iPartition, now compatible with Leopard.
They ran into a bug in Leopard’s AHCI driver relating to large block reads, this of course being a problem for partitioning and defragging operations.
Until the bug is fixed, Apple gave them a work around which they've incorporated, and so it should be safe to use their software. Be aware that these temporary workarounds have a noticeable negative impact on performance.
[translation by msmith]
