Not really understanding the relationship between hotplug, cardmgr (PCMCIA), and usbmgr. Apparently, I can't use both cardmgr and hotplug at the same time. Okay, I can, but the kernel event daemon (keventd) and cardmgr will both start the networking scripts when I insert my wireless Ethernet card.
I haven't been able to get hotplug alone to work with my ethernet card, so I apparently have to run at least cardmgr. I guess this means that if I want to do USB stuff, I need to run usbmgr, which obviously doesn't try to start the networking scripts.. I guess it's good I don't have FireWire on my laptop, otherwise I'd have to see if there was a firemgr or similar program...
I suppose I probably just didn't properly set up hotplug..