All right, these are the steps I took:
1) Installed the Atmel drivers.
2) Made sure that they showed up in lsmod (usbvnetr and uhci)
-This is about the point where I started getting that "Please insert card" message. Following steps seemed to remedy that.
3) Aliased usb-controller to uhci in whichever file that was. I think it's /etc/modules.conf
4) The lines I had previously added to /etc/rc.d/rc.modules:
I commented those out, after having previously enabled them.
5) Rebooted, drivers and USB device were detected on reboot.
Note that the device shows up in iwconfig at this point, but not ifconfig.
6) Ran dhclient eth1, was told that eth1 isn't a valid interface or something. This is fine, because it allows ifconfig to magically see eth1.
7) Used 'ifconfig eth1 192.168.1.105 up' to set the IP address of the card.
8) Used 'route add default gw <Router IP>' to set up the routing for the USB wireless NIC.
9) Ran 'iwconfig eth1 mode Managed' because I use what LinkSys dubs an Infrastructure type wireless network (as opposed to Ad-Hoc)
10) Ran 'iwconfig eth1 essid <Router SSID>' to set the ssid to connect to.
11) Just for checking, ran 'iwconfig' and saw that signal strength was acceptable and that it did indeed have the MAC address of my wireless router.
12) Pinged router to make sure it was really there and then pinged external IPs to make sure access to the rest of the world worked.
13) Edited /etc/resolv.conf to contain 'nameserver <NameServer IP>' so that DNS lookups functioned correctly.
Hopefully you'll be able to get yours working. As a total Linux newbie, I'm still kind of lost as to exactly how whatever I did fixed things, but it did. Also, I have to repeat all of the commands every time I reboot the machine, but that's going to be an easy enough fix. If you have further troubles, I'll be happy to try and help if I encountered them during my bout with the USB wireless NIC.