Defiler, you got yours already?
cherrybomb, I found libusb, which is a multiplatform usb library, there's also a windows implementation. It's all very early releases (still on version 0.1.xxx) but there's a high activity percentile on the project.
found another usb library for Java. It's called jUSB. An incomplete implementation lives here (win32) and the linux one lives here. I can't see info about Mac, but the project does have a high activity percentile too.