Installed Leopard on my MacBook Pro 2.4 Saturday morning via the Upgrade option and it went smoothly. I then installed the newest Logitech drivers, and my MX Revolution works normally, actually a bit better.
The two problems I've had so far are:
* Parallels 3 gives an error when loading WinXP; but it still runs fine.
* Drivers for Canon Pixma MP600 crash. I can scan, but then the software crashes. Haven't tried printing yet. Canon says they're working on it.
There may be other lurking issues, but I've not explored the new features yet. In general, it runs well.