Upgrading usb_modeswitch to 2.0.1 got my Vodafone K4201 USB modem working too in Kubuntu 12.04. I had just about given up getting it to work before seeing this thread.
It now switches automatically when plugged in, although oddly, it appears as another wired network connection rather than a Mobile Broadband connection in the network manager. Possibly because of the network range reported in the network manager (192.168.*.*).