M-Audio has released a new FireWire driver for Mac OS X Leopard 10.5.2.
This driver update is available immediately for the following devices :

FireWire 1814
FireWire 410
FireWire Audiophile
FireWire Solo
NRV10
Ozonic

This driver does not support ProjectMix I/O or ProFire Lightbridge.

Over at CDM, Peter Kirn has a rundown of the status of music drivers for Windows Vista & Leopard.
Leopard music making has had a few hiccups, but it really doesn’t look good for Vista music making:

Digidesign + Vista
Digidesign Windows OS Requirements
On the Digidesign side, the good news is Pro Tools 7.4 LE and M-Powered are [...]