So plug your other devices into the hub and reserve one dedicated USB port for the iPhone.
Absolutely ridiculous statement. What about all the other devices that need to be plugged into the Mac's USB ports directly. As they said 'my computer's 3 USB ports are already crowded'. There are just too many devices that only work when plugged into the Mac's USB ports. I have spare ports on my powered hub, and on my cinema display, but they're utterly useless for most things - and even fewer things work now with Leopard.
All these USB problems are just incredibly annoying. I spent ages trying various USB PCI cards because I preferred the option of having it fitted internally (and avoiding yet another power socket) only to discover that there aren't any that work reliably in my G5. I then resorted to a USB hub, which I managed ok with using Tiger, but now Leopard has stuffed that up too. Ridiculous putting 3 ports on the Mac, and then having many devices that won't work with hubs.