Pete,
I just got my SD430 to work with Leopard in Wireless remote capture, but this is how I had to do it. I don't know if any of this applies to you, but here goes-
1. I am using Windows XP running under VMWare Fusion. According to Canon, wireless remote capture that worked on my iBook with the PowerPC chip is not compatible with the Intel Chip in my MacBook Pro.
2. I loaded the enclosed software in XP and then went and got the upgrade to ZoomBrowser EX ver. 6.1.1, and made sure the USB port was working under XP. Also, I hooked up a third-party USB Wifi Adaptor that I was using to link the laptop and the camera in order to access the network directly from XP . The camera would not link via the network between Fusion and the Mac OS.
3. Once I hooked up the third-party adaptor was hooked up and XP saw it, everything worked as ordered. I have to give credit to WoodyZ and the VMWare Fusion discussion forum for the help in figuring out the use of the third-party adaptor. A simple fix but one that they helped me with, and I probably would not have figured out on my own.
I know that all of that may seem like a real pain, but it works great and it relly was not as hard as it may sound. I hope that helped. Email me if I can help in any other way.