Given that I only had to install the software because the shiny new fresh-out-of-the-box widget was refusing to speak to anything over wifi, this does not impress me. I think I'll be sticking with my working Vodafone stick, thank you very much.
For anyone else who runs into this, the fix appears to be to start the Vodafone Mobile Connections software, wait while that reinstalls all the drivers that 3 blatted, then restart the Vodafone software so it finally detects the stick.