Other World Computing is offering a FireWire 800 firmware update for their Mercury Elite FW800 external drives.
While Oxford Semiconductor and Apple Computer disagree over what has led to this issue (there is absolutely no issue under any circumstance with OS 10.2.8 and earlier), Apple has confirmed that the issue is limited to firmware v1.02 and prior.
The patch is also available through VersionTracker.
LaCie has also published a announcement on their website regarding their FW800 external drives.
WiebeTech follows suit for their Fire800 and MicroGB+800 products with an announcement on their tech support page, and offers an firmware updater.