Got a new 3G stick, the K3805-Z, which supposedly gives broadband download speeds and better than broadband upload speeds (5.76MBit/s). Bit of a problem to get this working under Ubuntu Natty. Doesn't work out of the box.
Shows up in the Ubuntu network panel, and you can connect, but it doesn't.
Downloaded the latest Vodafone Mobile connect (2.25.01), and installed. Now the modem no longer shows up in the network panel, but I can use vodafone-mobile-connect-card-driver-for-linux to connect. Doesn't create any routing table I would recognise, but it somehow works. Beats me.
Download speed test wasn't very good, got only 1.7Mbs, but upload was 1.12Mbs, which is better than I get with my ADSL2 connection.